Travel Tips & Travel Answers

We’ve all been there—the small child kicking the back of your seat, the lack of legroom, the war over the armrest. While there’s no fail-safe way to guarantee an aisle seat in the exit row near the front of the plane with no one sitting next to you, there are some tactics that can help. Check out the following tips for nabbing one of the best seats on a plane.

Not all coach seats are created equal. Exit rows, aisle or window seats, and seats close to the front are typically considered the best seats on a plane.

On a short business trip, you might want an aisle seat near the front of the plane so you can debark as quickly as possible on arrival. On a long-haul or overnight flight, you might prefer to have a coach seat next to the window so you can rest your head. The drawback is that you’ll need to disturb your seatmates each time you need to go to the bathroom. Nervous flyers may want to sit toward the middle of the plane over the wing, where there is less turbulence.

Exit row seats usually offer a bit more legroom, but they’re not appropriate if you’re traveling as a family. Children under 12 or 15 years old, depending on the airline, are not permitted to sit in exit rows, and by U.S. law infants are not allowed in the rows immediately behind or in front of an exit row either. Larger planes often have two exit rows, but it’s wise to avoid the first one, as the seats often will not recline. It is also important to note that if an emergency does occur, you will be expected to help out.

Many flyers also like “bulkhead seats,” which are the seats directly behind the physical barriers (such as walls, curtains, or screens) that separate different parts of the plane. Because there are no seats in front of you, you won’t get stuck with another passenger reclining into your lap—and you often get some extra legroom as well.

But be careful: Not all “bulkhead” rows are created equal. On some planes the first bulkhead row may be cramped and uncomfortable, or close to restrooms and noisy galleys. Also, keep in mind that you won’t have a spot to stow a personal item under the seat in front of you for easy access. Some planes offer bassinets for babies at the bulkhead wall, so you could be forced to spend the flight in close proximity to a crying child.

Each airline presents a unique set of challenges to flyers, say the experts at SeatGuru: “Not all legroom is equal since there is no industry standard. Before booking your flight, take a look to see which airlines fly that route and then check to see how they stack up against each other.” For more information, go to SeatGuru.com, where you can check out seat maps for nearly every type of plane on every major airline.

Keep an eye on seat pitch, especially if you’re tall. This is a measure of how much space there is between a seat and the one immediately behind or in front of it—so the higher the number, the more legroom you will have. SeatGuru lists both seat pitch and width (when available) for most airlines, and indicates the location of power ports or personal TV screens at each seat. Keep in mind, though, that the aircraft type could change at the last minute, so you can’t be absolutely sure about the configuration until you step onto the plane.

If you’re looking to sit in the safest part of the plane, opt for a seat near the rear.

The middle seat in any row is generally undesirable. (Don’t miss SmarterTravel’s tips for surviving the middle seat if you get stuck there.) 

Rows near flight attendant areas and restrooms tend to be noisier and have more traffic, and seats very close to overhead movie screens can be uncomfortable or too bright if you are trying to sleep. SeatGuru also identifies other potential problems on its seat maps, such as limited recline or reduced seat width.

So how can you avoid the pitfalls above and land one of the best seats on a plane? Follow these tips.

This is the most reliable tactic you can use. Providing your frequent flyer number at the time of reservation goes a long way toward netting you a good seat, especially if you are a loyal, high-ranking member. Elite flyers tend to be first in line for upgrades.

To achieve status, you’ll have to fly at least 25,000 actual air miles in a calendar year on one particular airline or its partners. Hang onto your boarding passes until you check your online account to ensure your miles have been credited. Once you’ve racked up some frequent flyer miles, you may use them for seat upgrades. Boost your earning power by signing up for an airline-affiliated credit card with signing bonuses of 40,000 miles or more.

The number of seats available for pre-assignment dwindles as the travel date approaches. SeatGuru says that usually you can’t choose good seats the day before your flight since most of the best airplane seats go quickly. The earlier you book your flight, the more seats are available and the bigger your pool is to pick from. Try for a flight on a Tuesday or Wednesday when it’s less busy, leaving more middle seats open so you have more wiggle room beside you while sitting on the aisle or by the window.

If you can’t buy your tickets at least several weeks in advance, be sure to check in online as soon as possible before your flight to select a seat, or arrive at the airport early if online check-in isn’t available. When you’re seat shopping, don’t assume business class costs much more than coach. Sometimes you can get a nonrefundable deal for a seat in first or business class for just a bit more.

Many airlines now offer economy-class seats with extra legroom for an additional fee. For example, JetBlue’s Even More Space seats, many of which are in exit rows, have up to seven extra inches of seat pitch. United offers Economy Plus access to high-ranking frequent flyers and to any travelers who pay the annual fee. This entitles you to a few extra inches of seat pitch toward the front of the coach cabin. (If any Economy Plus seats are still available at flight time, they can be purchased on a one-time basis.) Other airlines offer similar programs.

Make sure you understand what you’re getting for the money. You may be closer to the front of the cabin, but that might be all you’re buying since no perks (like meals) come with your “upgraded” coach seat.

Most airline websites and booking engines allow you to choose a seat when you purchase your ticket, or to return to your reservation after your initial purchase and select a seat later. In many cases, this process is free, but some airlines have added fees for advance seats. If you don’t see a seat you like, return to your reservation as your trip date approaches to see if anything has opened up in the meantime. If you don’t like your online options, try again at the airport, either at check-in or at the gate.

If you try to select your seat once you’ve booked your flight, you might see only the more expensive premium economy seats are available. That doesn’t mean you won’t get a seat eventually. In fact, you may get the premium economy seat anyway when you check in online—without having to pay extra.

Most airlines allow passengers to check in online up to 24 hours before their flight departs. At that point you can confirm the seat you’ve already chosen or select a better one. Watch for last-minute offers for discounted upgrades on premium economy and business-class seats. Failing that, many airlines hold back the exit rows and bulkheads—the most coveted seats in economy class—until the day of flight so they can be assigned at the airport. You still have a good shot of getting into those more popular rows.

Consider calling the airline directly if online seat assignment is not available. You can also confirm your seat the week you’re flying in case better seats have opened up. Check again a few hours before flight time to see if a good seat has become available.

Short on time or don’t want to keep looking? You can set up a seat alert through ExpertFlyer.com. A single alert is free, but subsequent alerts are charged at $0.99 each.

If you check in too late or arrive too late at your gate, the airline might give away your seat. Follow the airline’s guidelines about how far in advance you should arrive for domestic and international flights.

Long gone are the days when asking sweetly could get you a first-class upgrade on a flight, but it’s worth a try if you’re not satisfied with your current seat assignment. Once you reach your gate, ask whether any new seats have opened up. If other passengers upgrade to business class or don’t show up for the flight, you might get lucky and grab a better seat assignment.

If you know exactly which seat you’re interested in, it can be easier for agents to get it for you. Instead of asking for “a good seat,” try asking for “an aisle seat near the front” or “an exit row seat.” You’ll be more likely to get what you want (or an acceptable substitute). Ask again before you board. Sometimes gate agents are able to reassign seats at the last minute.

If you still don’t get a desirable seat, wait until the plane doors close. You may be able to move to an unoccupied seat. Check the last rows in the plane since they are often the last seats assigned.

If you have a disability or medical condition, or you need to sit next to your small children, let the agent know. Most will do their best to accommodate you.

Approach airline agents with courtesy. They hear complaints and demands all day. Speak to them kindly, and you may be surprised. Says SeatGuru, “Keeping the phrase ‘treat others the same way you want to be treated’ in mind and following that can unlock a lot of doors for you.”

 While you always want to be comfortable during your travels, part of staying safe in an unfamiliar place is dressing to blend in—or, at least, not dressing to stand out. Keep in mind local customs and attitudes, as well as religious beliefs, when choosing what to wear while traveling, especially abroad. Whether it’s because you’ll stick out like a sore thumb overseas or you’ll be uncomfortable on a plane, here are 10 things you should avoid wearing while traveling, as well as ideas for what to wear instead.

Research your destination, opt for modest clothing in more conservative destinations, and cover up appropriately when you’re visiting religious sites. Tank tops and shorts—as well as shirts with distasteful logos or words—can be considered offensive in many Middle Eastern and Asian countries, and many churches in Europe have strict dress codes.

In some parts of the world, women should avoid miniskirts, tank tops, bra tops, and sometimes even shorts and capri pants. Revealing dresses and cleavage-bearing necklines may also make you stand out in conservative countries. Men should avoid shorts and sleeveless tops in many Middle Eastern countries, or when entering a church or other holy place.

 What to wear: Pants and long skirts are a safe bet, and women may want to carry a shawl in their bag or purse just in case. As a general rule, travelers should cover their shoulders and knees when entering any church or holy site to avoid unwanted stares or being denied entry. It’s also wise to keep your feet and ankles covered. When in doubt, stick to long sleeves, and men, keep that chest hair concealed. 

Never wear expensive, flashy jewelry when traveling abroad, unless you want your diamond ring, pearls, or pricey watch to be tagged for someone else’s collection. You may also be more likely to misplace your cherished jewelry while traveling. Instead, leave the valuables at home.

What to wear: If you must have a little adornment, bring one or two costume pieces that will go with your outfits. And if you choose to wear your engagement ring, turn the stone to the inside of your hand on public transportation and in large crowds.

“Impractical” covers a wide range of bad footwear choices, including flip-flops (unless you’re at the beach), high heels (unless you’re attending a formal event), and brand-new shoes (because wearing shoes that haven’t been broken in is just asking for blisters). While sneakers are supportive, it’s wise to stay away from all-white trainers that will just get dirty—and mark you as an American tourist.

What to wear: Consider the climate and the activities you’ll be doing on your trip. Generally speaking, the key is to pick comfortable, supportive shoes in neutral or darker colors—and don’t forget appropriate socks. If you’re traveling anywhere but a beach, stick with closed-toe shoes, which can help prevent insect bites or cuts on your toes from gravelly surfaces.

We’re all for expressing yourself, but when you travel, bright colors aren’t always the way to do it. You’ll stick out more in many destinations, and if you spill your gelato, it’s going to be harder to hide that stain. You want to blend in, not draw unwanted attention to yourself (and nothing does the latter better than a neon green tank top).

Avoiding certain colors can even keep you safe. In sub-Saharan Africa, where tsetse flies transmit a potentially fatal disease known as trypanosomiasis, the CDC recommends wearing “neutral colors that blend with the background environment” because the flies are attracted to bright or dark colors.

What to wear: Unless loud colors or bold patterns are the norm in your destination, consider sticking with conservative hues like navy, blue, tan, and gray—and you’ll rarely go wrong with classic black.

Jeans are always a reliable choice, right? Not necessarily. If you’re traveling to a warm and/or rainy climate, consider alternatives; jeans don’t breathe well and take a long time to dry, making them impractical for many itineraries involving the outdoors. Skinny jeans can be uncomfortably tight on long flights or train rides, while baggy or ripped jeans may look disrespectful if you wear them into churches, mosques, or other holy sites.

Meanwhile, you’ll probably look similarly out of place by wearing hiking pants or sweatpants on the streets of large cities.

What to wear: Research your destination’s weather and cultural norms before you start packing to make sure your choices will help you fit in and stay comfortable.

Avoid clothing with sporting, religious, or military symbols, swear words, national flags, and any words or symbols written in a language you cannot translate. There’s no need to unintentionally spark an emotional debate while on vacation or to risk being kicked off a plane for wearing something the airline doesn’t approve of.

Be wary of hand gestures, both making them and wearing clothing depicting them, because these can have different meanings depending on where you are. (In Bangladesh and other parts of the world, for example, the “thumbs up” gesture is considered obscene.) Since you may never know what certain images suggest in another country, avoid them to keep from offending anyone.

To make yourself less of a target, you may also want to leave religious jewelry at home, or wear it under your clothes so it’s not visible to anyone.

What to wear: When in doubt, opt for clothing with solid colors or simple patterns, available from brands such as Ann Taylor, Everlane, Banana Republic, and Uniqlo.

Please, we beg of you, don’t be that tourist. While we all want the perfect vacation Instagram, we don’t want to be hit in the head by your selfie stick. The same goes for tablet-sized cameras and other large tech accessories. Stick to snapping pics with your phone or an actual camera to avoid injury and inconvenience to those around you.

And unless you’re a serious photographer, reconsider walking around a busy city with a huge camera hanging around your neck. Not only will you stand out, but you may also be targeted by thieves.

What to wear: Between uses, always keep your phone or camera stored safely in a zipped purse, camera bag, or pocket.

Backpacks and large purses tend to be impractical for urban sightseeing—do you really want to lug all that weight around? They’re also appealing targets for thieves, who can easily reach into an unzipped tote or sneak something out of a backpack while you’re wearing it on a busy subway train.

What to wear: Cross-body bags are one of the best options for travel, but any bag that fully zips will make you less of a target for thieves. Sling bags are another, gender-neutral option.

We’ve all been there. You packed a dress for a wedding, only to unpack and discover it’s a wrinkled mess. Or you thought jeans would be a good idea on the plane, and now they’re cutting off your circulation mid-flight. From discomfort to wrinkles and funky odors, the fabrics you choose can make or break your travel days. Avoid silks, nylon, leather, rubber, and, more generally, clothes made from a non-performance synthetic material.

What to Wear: Check the weather at your destination and keep in mind your activities. Some foolproof fabrics for packing and travel are moisture-wicking activewear, cotton, jersey, and clothes marketed as wrinkle-free.

Unless you’re skiing or taking on another outdoor winter adventure, leave the oversized jacket at home. This will save you space, weight, and hassle when packing.

What to wear: Layering is your friend. When traveling to a cooler destination, pack a few longer sleeved shirts as a base, then layer sweaters and a looser, lightweight winter jacket. Luckily, many travel and outdoor recreation companies are coming up with lighter down jackets that can be compressed into a small pack, such as this option for men or this one for women.

No matter how often I cover the problems that come with collision damage under car rental insurance, consumers continue to share their frustrations. A reader recently emailed me:

“I’m interested in finding a complete bumper-to-bumper, ‘drop off the keys at the counter’ car rental coverage when I travel. I recently thought I had complete coverage though a credit card, but when my car suffered a small dent, the car rental company flat-out refused to document that it actually lost income from having the car rental in the shop (which took three weeks to repair a small dent). I was left with responsibility.”

This experience is uncommon, but not unique. Car rental companies desperately want you to buy their collision damage waiver, or CDW (sometimes also known as loss damage waiver, or LDW), and will go to great lengths to make you pay for even the smallest damages if you don’t. Here’s what you need to know before you shell out for car rental insurance on your next vacation.

When you buy a CDW, the rental company surrenders its rights to charge you for damage to a car rental—with a few exceptions, such as tire damage or gross negligence. (CDW terms and conditions vary by car rental company, so you’ll want to read them carefully before committing.) But otherwise, no matter how banged up the car could be, you’re off the hook: Just turn it in and be on your way. No other approach—your own insurance, your credit card, or a third-party policy—is as comprehensive or convenient. If you want that full flexibility and peace of mind, pay for CDW. 

Typically, a CDW starts at around $30 per day and can go higher. It sometimes costs even more than the base car rental rate. The actuarial cost to the rental company—the amount it would allocate toward a damage pool based on risk experience—is probably just a few dollars a day; the rest is theirs to keep. No wonder the agents push it so hard: It’s clearly a lot more profitable than the car rental alone.

You can cover your major damage responsibility by relying on your own insurance, a credit card with insurance, or a third-party policy. But in all of those cases you have to pay a damage claim up front, then recover as much as you can (all of it, you hope) by filing a claim afterward. That means signing a credit card bill for hundreds or even thousands of dollars when you return the damaged car, and not knowing if you’ll get that money back.

That’s why many rental companies won’t accept rentals via debit card, or a credit card with a small limit. If you can pay the initial rental fee with a debit card, you’ll still need to provide a credit card to cover a possible damage claim, which would be filed before you can leave the return counter.

If you don’t buy CDW, rental companies can charge for more than just fixing the damage. They also charge for:

• “Loss of use,” meaning the potential revenue lost while the car is out of service being fixed, even if the company had lots of other cars available. And they generally figure that daily loss at the full retail rate.
• Towing charges, if you are unable to drive the car back to the return station.
• “Diminished value,” or the potential loss of the car’s resale value (because of your damage) when the rental company disposes of it, usually within two years.
• Administrative fees associated with the claims process.
• 
  

Most non-CDW car rental insurance will cover those extras. But, in some cases, coverage depends on cooperation from the rental company—and it may not be forthcoming, as our reader’s above wasn’t.

In many cases, if your regular auto insurance covers collision damage to your insured car, it also covers damage to a short-term rental. But this coverage is generally limited to driving in the U.S. and maybe Canada, and won’t cover car rentals in Mexico, Europe, or anywhere else. So, before you plan on using your own insurance, check its coverage. If it does cover rentals, you can place a claim on it. Still, you must typically pay your policy’s deductible, and any claims may cause your rates to go up.

These days, most credit cards provide “free” collision coverage for car rentals, provided you use the card to secure the rental. A sample credit card benefits statement describes coverage as:

“Physical damage and/or theft of the covered rental vehicle. Valid loss-of-use charges assessed by the rental company while the damaged vehicle is being repaired and is not available for use, as substantiated in the company’s fleet utilization log. Reasonable and customary towing charges related to a covered loss to take the vehicle to the nearest qualified repair facility.”

Note that this typical Visa card’s benefits do not cover diminished value or administrative costs. A few premium credit cards offer primary collision coverage, meaning the card takes full responsibility for the payment. But coverage on most cards is secondary, meaning the card picks up only what you can’t first recover from your own insurance. And you still have to pay the rental company up front, then file for reimbursement from your card issuer.

Another gotcha in the above fine print: This card (and many others) pays for loss of use only if verified by the rental company’s log. Unfortunately, some rental companies don’t cooperate with credit card issuers in providing this type of documentation in a timely manner.

If you rent a car through one of the big online travel agencies (OTA) such as Expedia or Priceline, the agency normally offers you the option to buy collision coverage for around $10 a day. That coverage is provided by a third-party insurance company such as Allianz. The cost is a lot less than the rental company’s CDW, but, as with credit card coverage, if you damage the car, you have to pay up front and claim later.

Typical third-party collision coverage includes about the same contingencies as credit card coverage, but because it’s grouped with the booking you won’t have to make any other claims. You can also buy collision coverage independently: Bonzah, for example, sells coverage at around $9 per day.

You should never get behind the wheel of a car—or lawnmower, for that matter—without liability protection. But you don’t buy that from a car rental company: It usually comes with household, homeowner, or tenant insurance, and it covers far more than a car rental. And if your net worth is in six figures, you probably need an “umbrella” liability policy that covers a million dollars or more.

Car rental companies in most countries are required by law to include liability insurance. In the U.S., required coverage can be ludicrously small (usually only the minimum required by the state)—it’s usually much better in Europe. If you don’t have substantial liability insurance, you might consider buying the rental company’s offering. Still, your best bet is to make sure you’re covered 24/7 with your own insurance so you can forget about the rental company’s overpriced insurance.

The takeaway from all this: No alternative source of collision damage coverage—your auto insurance, your credit card, or a third party—completely isolates you from risk. Lots of travelers successfully rely on lower-cost alternatives to CDW without encountering any problems, sure. Occasionally, however, your own insurance, credit card, or third-party policy may not cover an unusual charge a rental company might impose.

If you’re unwilling to accept any risk at all, you might want to buy that overpriced CDW. For most travelers and circumstances, credit card or third-party coverage is sufficient, and primary coverage is a lot better than secondary.

There’s an art to packing a carry-on bag. Wise travelers must balance the requirements of airlines and airport security, make sure important items are easily accessible, and remember all the little things that will keep them comfortable in flight.

In the spirit of 10 Things Not to Do When Checking a Bag, we’ve gathered seven common carry-on bag mistakes. Steer clear of these, and you’ll save money, have a better flight, and avoid running afoul of airport security.

Let’s start with the basics of how to pack a carry-on: If you’re traveling with a full-size bottle of shampoo or sunscreen, it must go in your checked bag, not your carry-on. The world’s airports restrict liquid/gel items in your hand luggage to bottles no larger than 3.4 ounces (100 milliliters); they all must fit within a single quart-size (or liter-size) zip-top plastic bag.

This means that if you’re going to pick up a bottle of water or soda for the plane, be sure to buy it and stow it in your carry-on after security, not before. (Don’t be that bleary-eyed traveler who shows up at an early-morning checkpoint with a cup of coffee you just bought, only to have to throw it away.)

Note that there are a few exceptions to this rule, including essential medications and food for infants or children.

Each country’s government has slightly different rules about what can and can’t be brought aboard a plane, but as a general rule you should never put any of the following in your carry-on: firearms, explosives, baseball bats or other sporting equipment that could be used as weapons, self-defense sprays (such as mace), and sharp objects such as knives and safety razors.

Scissors are generally okay when packing a carry-on, as long as the blades are shorter than 4 inches (or 6 centimeters in some countries). Nail clippers and disposable razors will also pass muster in most parts of the world. Swiss Army knives, however, are a no-go. Snow globes are not permitted unless they’re small enough to fit inside your quart-size plastic bag with the rest of your liquids and gels.

You can find lists of prohibited items for the following destinations at the links below. If you’re flying to or from a different country, do a Google search for its security rules, or call your airline.

• United States
• Canada
• European Union
• Australia
• New Zealand

Save time in the security line by making sure your plastic bag of liquids and gels is right at the top of your carry-on or in an easily accessible pocket—that way you’re not digging around for it while the passengers behind you tap their toes in irritation.

The same goes for a laptop computer; unless you’re in an expedited travel line (such as TSA PreCheck in the U.S.), you’ll have to take this out at the security checkpoint for screening.

You’re aware that checked bags are subject to extra fees if they’re overweight or oversized—but did you know that many airlines weigh carry-on bags as well? Both Qantas and Air New Zealand, for example, have a 15-pound weight limit for carry-on bags (7 kilograms), while Air France allows a more generous 26 pounds (12 kg) as the total weight of your carry-on plus your personal item. Consider buying a small luggage scale to weigh your bag before you leave; that way you can redistribute or discard items in the privacy of your home rather than at the airport counter.

Many other airlines, including the biggest U.S. carriers, do not currently have weight limits for carry-on bags, but they do have size limits—and unfortunately, they’re shrinking. See Carry-on and Personal Item Size Limits for 32 Major Airlines to see how your airline stacks up.

Even if your bag is perfectly within your airline’s weight and size limits, you might still have to check it at the gate if the plane is very full or it’s a smaller aircraft than expected. Just in case this happens to you, make sure everything truly vital—travel documents, pricey gadgets, medicine—is stowed in the personal item you keep with you, not in the carry-on you gate-check.

Also, make sure there’s a luggage tag on your carry-on; gate-checked bags are occasionally mishandled just as regular checked bags are, and you’ll want your contact information on the bag in case your airline sends it astray.

Especially for longer flights, you’ll want to stock your carry-on bag with must-haves such as earbuds/headphones (some airlines charge for these), antibacterial hand sanitizer (to help you avoid in-flight germs), an eye mask, a travel pillow, and plenty of reading material. For more ideas, see The Essential Carry-on Bag Packing List.

Some low-cost carriers, including Spirit and Frontier, charge fees not only for checked bags but also for carry-ons. You will pay the lowest possible fee for your carry-on if you pay it online in advance rather than when you arrive at the airport. If you know you’ll be bringing a carry-on aboard your flight, pay for it when you book. 

 The U.S. State Department issues two versions of a passport: a traditional passport book and a passport card. Not only do they look different, they serve slightly different purposes. The passport book has plenty of pages for visas and arrival/departure stamps, while the passport card is a one-piece credit-card-sized ID card. Which you should get, passport book vs. passport card, depends on how you plan to travel and how much you want to pay for your travel documents.

The standard passport book covers all the bases: It’s all the U.S. government requires for you to enter a foreign country and re-enter the United States on your return trip. First-time application fees total $145 (a $110 application fee and a $35 acceptance fee). Many foreign countries require nothing more for entry than a U.S. passport book, although some also require visas.

The passport card, meanwhile, is both less expensive and less flexible. The passport card can be used only to re-enter the U.S. from Canada, Mexico, the Caribbean, and Bermuda at a land border crossing or sea port-of-entry, although these areas generally accept it as valid ID for entry as well. You cannot use the passport card for international air travel, even when you re-enter the U.S. by land. The first-time fee for a passport card is $65 ($30 application fee and $35 acceptance fee).

ou can get both a passport book and a passport card for $175 ($140 application fee and $35 acceptance fee).

Passport books or passport cards are both valid for 10 years after issue for adults, and five years for travelers under age 16. The State Department’s website offers complete details and an online application form.

Obviously, it’s far more useful to have a passport book vs. passport card in most cases where you plan to travel internationally. But if your international travel consists entirely of surface trips in the limited areas covered by the passport card, the card is both cheaper and a tad more convenient to carry and use versus the passport book.