What is a "backpack"?

A backpack is a type of bag that is carried on the back using two shoulder straps. It is designed to evenly distribute the weight of the contents over the wearer's back and shoulders, making it comfortable to carry for long periods. Backpacks are often used for outdoor activities such as hiking, camping, and backpacking, as well as for everyday use such as commuting to work or school. They come in a variety of sizes, shapes, and styles, with features such as multiple compartments, water bottle holders, and padded straps for added comfort.