A CV Boot is a rubber casing that encloses the CV Joint, protecting it from water, tar, grit and debris from the road.
Constant-velocity joints (aka homokinetic or CV joints) allow a rotating shaft to transmit power through a variable angle, at constant rotational speed, without an appreciable increase in friction or play. They are mainly used in front wheel drive and all wheel drive cars. Rear wheel drive cars with independent rear suspension typically use CV joints at the ends of the rear axle halfshafts, and increasingly use them on the propshafts.
The shaft connecting the Transmission Output shaft to the Differential Pinion shaft. It transmits power from the transmission to the Differential. It is found primarily on rear-drive vehicles. There is usually a Universal joint on either end. Also called propeller shaft.