Backpacks are utilitarian. They are probably the most efficient way to carry a lot of things with you. They come in a variety of sizes, and you can suit the size to the occasion, from a small camelback holding a few snacks and water necessary for survival on a dessert run to a giant backpacker’s sack full of all the comforts and warmth needed in the high, winter mountains, you can take anything your strength can endure. They allow you to keep documents tidy and dry as you shuttle between places on a bike. They enable you to carry the necessary change of clothes and lunch for work. They give the luxury of taking a game, book or other entertainment wherever you might go. You can keep supplies for changes in weather, which can be frequent and both predictable and erratic in the high Arizonan desert. They are easy to access and stash, but you can also weave the pull strings on the zippers together to give some measure of security to what you are carrying as you navigate large-city public transportation throughout the world. Each time I put on a backpack, I have a small sense of adventure waiting for me and the feeling of ease at being prepared. There are items that I have in my backpack all the time: a headlight, rain coat, hat and gloves, pencils and pens, battery/charger, and some cash stashed in a hidden place. Other items are common, such as my planning/grading binder and laptop, while others float in and out as occasion arises. No matter what, I can go through the content in my mind to confirm that I am prepared for what is coming. I also have something on the order of 14 backpacks. I have only actually purchased about two of these, but people seem to have an inherent sense of my propensity for backpacks as I am gifted them frequently. The best are those with several pockets on both the inside and the outside. Inside allows for hiding and organizing, while outside prevents backpack blowout as you try to get a pen but end up with everything from a spoon to a chemistry textbook all at once. I have enough that I can have set packs for various activities, such as my climbing pack, camping pack, traveling pack, and every day pack. As with so many things, the combination of utility and versatility is one of the major factors in backpacks being so awesome.