Temperature is the measure of the amount of heat energy that a body posseses. Heating an object causes the atoms in the body to vibrate. Thus temperature is caused by oscillation of atoms. At absolute zero temperature, there are no oscilltions.
well, to have a temperature you just need "particles" that are accelerating and decelarating randomly. that implys radiation; electromagnetic theory states that accelerating charges radiate. so, if you have more acceleration you'll have more radiation. and this radiation caused by heat is absorbed by the environment and is transformed again into random accelarations, and so on.. indeed to describe the "vibrating particles" better, think of electron and the nucleus doing simple harmonic motion. so thats all about electromagnetics and statistics.
Added after 7 minutes:
Lord Loh. said:
.... At absolute zero temperature, there are no oscilltions.