An electric bicycle, also known as an e-bike, powerbike or booster bike, is a bicycle with an integrated electric motor which can be used for propulsion. Many kinds of e-bikes are available worldwide, from e-bikes that only have a small motor to assist the rider's pedal-power (i.e., pedelecs) to somewhat more powerful e-bikes which tend closer to moped-style functionality: all, however, retain the ability to be pedalled by the rider and are therefore not electric motorcycles.
One reason for doing so is the way it is powered, which works in a manner that would be familiar to someone accustomed to a manual transmission car. Like a car, you start in a low gear and work your way up as you gain speed. Since the motor runs through your transmission as opposed to applying power directly to the axle, the gear you’re in really matters. The importance of gearing connects you much more to the road and the terrain, which means you are a more active rider than when using throttle-controlled electric bikes.
E-bikes mostly use motors and battery options from a few major suppliers: Bosch, Yamaha, Shimano, and Brose. A few other brands exist, but are less reliable or powerful. Some, like the Yamaha system, have more torque and others are quieter. But generally all four make good options. Look for motor output (in watts) which will give you an idea of total power. But watt hours (Wh) is perhaps a better figure to use—it takes into account battery output and life to give a truer reflection of power.