The best backpacks — the ones that last the longest — have all the following characteristics that make them durable, protective, and long-lasting:

• Water-resistant material – While your pack does not need to be 100% waterproof, make sure your bag is made out of a semi-waterproof material so everything doesn’t get wet in a drizzle (many packs come with tarps you can put over them in case of a severe downpour). Moreover, make sure the material won’t stay wet long and thereby get musty. I look for material that is thick but lightweight. I should be able to pour a cup of water over it without the insides getting wet. I’m not traveling a lot during torrential downpours or monsoons, but I have been caught in small rainstorms before, and because my backpack is made out of a good material, I’ve never opened my bag to find wet clothes.

• Lockable zippers – Make sure each compartment has two zippers so you can lock them together. While am not really worried about people breaking into my bag and stealing my dirty clothes in a hostel, I like locking up my bag when I am traveling. I’m always paranoid that someone is going to put something in my bag or that a grabby baggage handler in an airport is going to take my stuff.
  When purchasing locks, make sure the package says they are TSA-friendly locks — these locks have a special release valve that allows the TSA to open the lock without breaking it so they can check your bag. You can purchase TSA locks at any large retail store, such as Target or Walmart.
  If your pack doesn’t have two zippers, you can always get Pacsafe (www.pacsafe.com), which wraps a lockable metal mesh around your whole bag and can be tied to a large object. It means that not only is no one breaking into your stuff, no one is walking away with it either. Pacsafe is a good form of protection for your bag, especially if you are going to be somewhere where your bag will be unattended for a long time. One thing to remember about Pacsafe is that this metal mesh also adds a lot of weight to your bag and it can be burdensome to carry around. Most people I know who use Pacsafe are photographers who carry a lot of expensive equipment around

• Multiple compartments – A good bag must have multiple compartments. This way, you can break up your belongings into smaller sections so it’s easier to access and find the stuff you need. For example, my clothes are in the main compartment of my bag, my umbrella and flip-flops in the top, and my shoes in the separated side compartment (that way they don’t get everything dirty). It saves having to dig around your bag.

• Internal frame – The majority of backpacks today are internal-frame packs, meaning the support rods and frame are built into the backpack and hidden from view. However, there some are still external-frame backpacks, where the rods are separate from the actual pack and stick out (think of those backpacks you see in old hiking movies or movies about people backpacking Europe in the 1970s — a big, clunky metal frame). Don’t get one of those. Make sure you buy a backpack with an internal frame. It not only looks better but the rods won’t get caught on anything and your bag will also be slimmer, making moving around easier. Additionally, internal-frame packs tend to be lighter as the frame is composed of a carbon fiber or tough plastic, which makes them easier on your back as well as more durable.

• Padded hip belt – Most of the weight you will be carrying around will be pushing down on your hips, so you’ll want a padded belt to make supporting the weight more comfortable. The belt will help provide support and distribute the load more evenly on your back, causing less strain. The hip belt should also be adjustable so you can tighten it for extra support.

• Padded shoulder straps – These make carrying your load more comfortable, as the weight of your pack will also be pushing down on your shoulders. The pads will put less pressure on your shoulders and also help take pressure off your lower back. Make sure the padding is very thick and made up of a single piece of material as it will be less likely to split and thin out.

• Contoured/padded back – A lumbar-shaped pack makes carrying it more comfortable, as it helps distributes weight more evenly — the same principle applies as is used in contoured chairs. It allows for a more natural arch ensure no back pain. Moreover, this type of pack creates a small space between your back and the bag, allowing air to move through and help keep you slightly cool (lugging your bag around can build up a sweat!).