As you’re reading through our reviews or researching the best backpacks yourself, you may see a profusion of various technical terms being thrown around regarding the materials used in a backpack. Questions start to cross your mind like, what are the benefits and drawbacks of nylon and polyester? What do all these abbreviations stand for? How did I end up reading Wikipedia for the last 3 hours? What is the answer to the ultimate question of life?

Don’t worry, we’ve been there too. So here is a rundown on all the different terminology, nomenclature, and technology being used in the latest backpacks, and even the not-so-new ones.

• Cotton canvas — back in ages past, backpacks were most frequently made of cotton canvas and then coated with wax to waterproof them. But these bags were heavy and prone to damage by abrasion. If they weren’t dried properly before being stored, they could start to rot and decompose. Today’s backpacks have switched over to using non-cotton fabrics, such as nylon and polyester. Few cotton canvas bags can still be found today but are blended with synthetic materials and are not waterproof. If you think back to any war movie where soldiers, sailors, airmen, or marines carry all their belongings in a large military-issued duffel bag, those are typically made of cotton canvas.
• Nylon — with the days of cotton past, nylon has become the go-to material for backpacks. Nylon is actually a whole family of synthetic fabrics. It’s a polymer that can be formed into various shapes and fibers through melt-processing. Basically, it’s plastic. While nylon has much better waterproof traits than cotton, it has the tendency to tear when punctured. However, this can be resolved by implementing various weaves and sewing patterns, which brings us to…
• Ripstop — Ripstop nylon is very commonplace now particularly for camping and hiking backpacks. Rip-stop nylon integrates a grid of thicker threads sewn directly into the nylon at close intervals. This prevents the issue of ripping or unraveling if the nylon is punctured and also helps waterproofing. On the other hand, if rip-stop is used in light fabrics, abrasion or regular use can cause holes to open along the seams more quickly than in other thicker fabrics, as lighter threads and the thicker ripstop threads wear at different rates. Ripstop is used in sails, parachutes, and hot air balloons and was originally developed in WW2 to replace silk parachutes.

• Ballistic — Once in awhile you’ll also see nylon that is termed “ballistic nylon”. This is a thick and durable nylon that was originally designed by DuPont for military apparel during WW2. Its name reflects the intention of protecting airmen from debris and shrapnel caused by bullets and shell impacts. It was, in short, the limited body armor used before Kevlar was developed, but is still used today for sporting equipment, motorcycle jackets, and tool/utility belts. Technically, ballistic nylon is woven nylon made in a 2×2 or 2×3 basketweave of varying denier, typically 840D to 1680D — it’s a very heavy nylon. More on denier below. The Aer Fit backpack is a high denier ballistic nylon.
• Polyester — aside from nylon, polyester is probably the most commonly used fabric in the post-cotton era. Also known as pack cloth, polyester is cheap and holds its colors well. This makes it a fabric of choice for school bags, particularly for backpacks intended for younger kids. In line with the old adage — you get what you pay for, polyester backpacks are not as durable as their nylon or canvas counterparts. Hence, lower end and cheaper backpacks are often polyester, while the more expensive products are often nylon.
• Polypropylene — PP is a thermoplastic polymer that is made by adjoining propylene monomers (ergo poly-propylene). PP is a very widely used plastic and you’ll see it in everything from ropes, to carpets, even in paper. If you’ve ever been in a wet lab in school, those plastic pipette tips are made of PP. Heck, even the stickers on a Rubik’s Cube are made of PP. Polypropylene doesn’t absorb water and dries quickly; it’s more hydrophobic than polyester. It’s a good insulator as it doesn’t transfer heat effectively. As such, it’s found its way into backpacks. Usually, you find tote bags or drawstring bags made of PP, but some backpacks also have components made of it. Unf