I don't watch anime, but I have a friend who does and she has talked on and on about it, so I know these terms:
Tsundere: Cold and hostile towards the people they like until eventually they show a warmer side.
Yandere: Acts sweet and innocent but is so creepily obsessed and possessive of their loved one that they'll do anything to keep him/her.
Kuudere: Acts cool and non-chalant but shows sweetness later on.
Dandere: Anti-social, doesn't talk until the right person comes along.
Which one are you?
I'm definetely a tsundere, sadly. I have quite a few stories to back me up XD