The backpack is arguably the most ubiquitous form of bag in the modern world. It takes on many shapes and is used in a wide variety of situations. Of course, the most traditional use of the backpack is for the transportation of possessions over long distances. In consideration of that fact, it may be said that backpacks intended for outdoor activities are perhaps the most "traditional." These backpacks are usually designed to allow one person to carry all the gear required for outdoor activities like hiking and camping. They are larger than the average backpack and possess a large number of straps and pockets, the better to transport a variety of items.



The necessity of carrying a large and varied number of items while camping or hiking makes a framed backpack very desirable. Backpacks used in outdoor activities generally fall into two categories, the first of which is the external frame. This is the most traditional type of framed backpack. It features a rigid external frame that may be strapped to the wearer's back using a complicated array of straps. Although such backpacks have been largely replaced today, they were used until very recently. There is evidence that wooden framed backpacks have been used for centuries. Metal framed backpacks, usually featuring lightweight aluminum tubes, became popular during the 20th century. Today, those external frame backpacks still used sometimes have plastic frames.

The second type of framed backpack is the internal frame. This backpack's frame usually consists of flexible metal or plastic strips, which mold to the wearer's back, providing a comfortable fit. When originally invented, internal frame backpacks suffered in popularity due to small load capacities and lack of comfort. However, newer models have overcome these problems and today, this kind of backpack has mostly replaced external frame versions. Like its predecessor, the internal frame uses an array of straps to allow the wearer to carry it.

External framed backpacks do have several advantages over the newer internal frame versions. The existence of an external frame provides a great number of lash points, or points at which items can be tied to the outside of the backpack. Such a method of carrying allows the backpack wearer to easily find any item that he or she may need to access regularly. While internal frame backpacks usually have a few lash points, it usually difficult to effectively tie large items to such backpacks. Additionally, because the external frame holds the cloth portion of the backpack away from the wearer, such backpacks are usually cooler to wear.

Of course, internal frame backpacks have their advantages too; else they would not be so popular. Although it is difficult to tie large items to these backpacks, the bags do feature large internal carrying capacities, which usually compensates for the lack of external lashing points. And while the close fit of these backpacks may make the wearer sweaty, such a fit also means that they sit better on the wearer's back. This characteristic can be especially useful if the wearer is doing something that involves upper body movement, such as scrambling over rocky surfaces.