- Killed by a hostile mob
- Fall damage
- Fire damage
- Suffocation (either in water or in solid blocks)
- Killed by another player
- Use of /kill
- Falling out of the world (or Void damage)
Upon death, different things may happen, dependent on gamerules and difficulty setting.
If the difficulty is set to Peaceful, Easy, Normal or Hard in normal Survival mode, then upon dying, you will have the option to respawn at your spawn point, which will either be the original area you spawned into, or to a bed, usually without anything in your inventory. If you are playing Hardcore mode, however, you will not have a respawn option, and your only option is to delete your entire world.
The only gamerule that affects death is keepInventory. If enabled, you will respawn with all your inventory. The alternative is having to run back to where you died to reclaim your items before they despawn.
In Survival and Adventure mode, you can die by any of the methods mentioned above. In Creative and Spectator mode, however, you can only be killed either by the /kill command or by exposure to the Void.
Whenever a mob dies, which can happen in any of the ways a player can die, with several exceptions, their skin is shaded red for a short interval, and they fall over on their side, and vanish with some brief wisps of smoke, leaving behind only some item drops and some experience points. Exceptions include the Ender Dragon, which floats up slightly and breaks down into beams of light, and creates a portal which may be used to escape the End.