DPS=Damage Per Second

[Furio]

also, nice ak gear

Wow, you're just sad...

Anyway:

DD = direct damage = a spell that does its total amount of damage upon hitting the target
DoT = damage over time = a spell that spreads its total amount of damage over a period of time
DPS = damage per second which is dealt regardless of the kind of damage (DD or DoT).

All classes use a combination of DD and DoTs.