The AR-15 is the most popular firearm in America. This category contains items specific to the AR-15. This includes both rifles and pistols.
The AR-15 (ArmaLite Rifle 15) is modular in design. This makes replacing parts very easy, even for those less inclined to tinker. It is common to upgrade AR-15 parts as time goes by. The modular design also lends itself to assembling your own from selected components. This sort of custom design is part of what makes the AR-15 so popular.
Many parts used on the AR-15 are also used on the AR-10/AR-308 platform. You can find these parts, such as grips and gas system components, in other categories.