In Minecraft, TNT can be use for a number of things ranging from epic explosions to unparallel destruction. However, it also has more creative and constructive uses. All of these are as follows.
TNT can be used for a very agressive mining technique called "Power Mining". However, this is a very inefficent way of mining due to the fact of how hard it is to obtain gunpowder in survival but is very useful to those in creative mode who wish to clear mass areas of blocks due to their ability to spawn items.
TNT can be "ignited" by applying power (from Redstone) directly to the block or through the use of "Fire".
In past versions of Minecraft **Mojang** TNT could be ignited with a hit from the player.