These are analogous to the terminals on a bipolar transistor, in that the source fulfills a similar role to the emitter, the gate to the base, and the drain to the collector. Thus the three basic ...

The transistor acts like an insulator or a switch that is turned off. When a positive voltage is applied to the base, electrons are pulled out of the junctions and they no longer act as barriers.

The Intel Pentium has a separate section just for multiplication by 3, which has more transistors than a Z80 had in total.

Electricity can race through. The transistor base (the "meat" of the sandwich) acts like the handle on a faucet. Turn it one way and current will gush through like water through a hose.

A slight surprise comes in how point contact transistors are used, unlike today’s devices their gain in common emitter mode was so poor that they took instead a common base configuration.