Fragmentation is the process by which the casing, shot, or other components of an anti-personnel weapon, bomb, barrel bomb, land mine, IED, artillery, mortar, tank gun, or autocannon shell, rocket, missile, grenade, etc. are dispersed and/or shattered by the detonation of the explosive filler.

The correct term for these pieces is "fragmentation"; "shards" or "splinters" can be used for non-preformed fragments. Preformed fragments can be of various shapes (spheres, cubes, rods, etc.) and sizes, and are normally held rigidly within some form of matrix or body until the high explosive (HE) filling is detonated. The resulting high-velocity fragments produced by either method are the main lethal mechanisms of these weapons, rather than the heat or overpressure caused by detonation, although offensive grenades are often constructed without a frag matrix.

These casing pieces are often incorrectly referred to as "shrapnel", particularly by non-military media sources.