Im in the process of looking for a digital camera, and there is one particular feature i would like but havent a clue what its called!!

Basically, if you taking a moving shot (say for instance a car on a track), what is the feature called so that the car itself is clear and in focus, rather than being half way up the road and blurry like me old mans camera!!!!!

Is this a common feature on most new cameras or have i limited myself??

Cheers
Chris