The forced crash.
A corrupted world is when Minecraft hiccups and plops a chunk from another world to a world. Backups may help.
No, That's not what I mean, I mean like the unloaded chunks that give out underground structures for example, Strongholds and Abondoned mineshafts and they don't cut out caves and they don't make lava or water flow down, they don't make your world corrupt. (sorry if any words are spelled wrong)
A other glitchy falling through floor thing in multiplayer after a creeper explosion in a survival games minigame.