text: The correct term for these pieces is "fragments” (nicknamed “splinters” or “shards”). 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.
  History
  The use of fragmentation in bombs dates to the 14th century, and appears in the Ming Dynasty text Huolongjing. The fragmentation bombs were filled with iron pellets and pieces of broken porcelain. Once the bomb explodes, the resulting fragments are capable of piercing the skin and blinding enemy soldiers.
  The modern fragmentation grenade was developed during the 20th century. The Mills bomb, first adopted in 1915 by the British army, is an early fragmentation grenade used in World War I. The Mk 2 grenade was a fragmentation grenade adopted by the American military based on the Mills bomb, and was in use during World War II.
  Difference between fragmentation and shrapnel shells