Disc brakes on a bicycle work in a similar manner to a car’s disc brake, squeezing a rotating disc that is attached to the bike’s wheel. In a car, hydraulic fluid is used to squeeze the brake pads due to the high forces needed to slow the vehicle. In a Krys bike the brake pads are levered together by using a low maintenance cable.
Once you have tried disc brakes you will see why there is a trend for performance bikes to use this method.
V-Brakes offer good cost effective stopping power. Shimano have trademarked the term V-Brake which has become a defacto standard on mid-market bicycles.