In a field-effect transistor, from which electrode do charge carriers enter the channel?

In a Field-Effect Transistor (FET), the source is the terminal where charge carriers (which can be either electrons or holes, depending on the type of FET) originate or 'source' into the device's conductive channel. The flow of these carriers is modulated by the gate before they eventually exit the device. The drain is where the carriers leave the channel, while the emitter is a term used exclusively for bipolar junction transistors.