Wear in the outer joint usually shows up as vibration at certain speeds, a bit like the vibration caused by an unbalanced wheel. To determine if the joint is worn, a driver should find a big empty parking lot and drive the car slowly in tight circles, left and right. Worn joints will make a rhythmic clicking or cracking noise. Wear in the inner joints shows up as a "clunk" or "pop" when applying power or, if severe, when lifting off the throttle.
Partial seizure causes a strange "pattering" sensation through the suspension. It is caused by the joint overheating, which in turn is usually caused by the outer joint gaiter/boot having split, allowing the joint to throw out its grease. If caught in time, one can clean the joint carefully, repack with grease and replace the gaiter/boot. Kits which include the grease, gaiter/boot, and retaining clips are available from most automotive manufacturers. Some universal gaiters/boots are split lengthwise enabling them to be fitted without having to disassemble the wheel hub and CV joint.
Good Old Wikipedia! Fairly sure Im having problems with mine at the moment, especially in the cold