Gate (of a transistor)
Beginner
The control connection of a transistor. Its voltage, an electric push, decides whether the switch is on or off.
Novice
The terminal that sits on top of the thin insulating oxide over the channel. It is not electrically connected to the silicon; it acts through its electric field, like one plate of a capacitor.
Expert
Polysilicon in older processes such as SKY130, a metal stack over a high-k dielectric in advanced ones. Its capacitance ( plus overlap and fringe) is the load every driving gate must charge. Not to be confused with a logic gate.