TNT, like other consumables, may randomly be dropped by mobs when killed. A player can then pick it up. Three TNT may be carried at a time.
When picked up, TNT remains above the player's head until they either are killed or throw all TNT they have by using the shoot bow button. Once it lands after being thrown, it starts charging; during this time, a circle appears around it, alerting the players of its massive 8 block radius. Once it finishes chargind, it explodes, dealing massive damage (about 2 times more then the Creeper's explosion) to any entity in its range, including players. This is not very effectively in boss mobs because they have too much health.