oav

Hello, As the title says I would like to know when to use the... abbreviations? So far as I know all anime titles start with an episodes and after the end of a story of anime there's an OAV or OVA airing out. I don't know the meaning of OAV, OVA after all the episodes. Also I want to know why...

I didn't see this on nyaa or bakabt, so it has to be really hard to find >.< http://www.animenewsnetwork.com/encyclopedia/anime.php?id=56 should I make a thread per anime req? (some I have, and would definitely like to see here~ :P)