CMOS
CMOS (complementary metal-oxide-semiconductor) is the trick that lets a chip pack billions of switches without cooking itself. Each logic gate pairs two kinds of transistor — an n-type that turns on when its input is high, and a p-type that turns on when its input is low — wired so that, in any steady state, exactly one of them is off. Picture a tug-of-war where one side always holds firm while the other lets go: the output is pulled hard to either the supply or ground, but no straight-through wire ever links power to ground.
Because that path stays broken at rest, an idle gate sips almost nothing — current flows mainly in the brief instant of switching, when the gate is charging or draining the next gate's input and, for a moment, both transistors conduct at once. Multiply that tiny per-switch sip by billions of gates flipping a billion times a second and you get a manageable few watts instead of a meltdown. This low standby power is exactly why CMOS displaced earlier logic styles like NMOS and TTL in the 1980s, and it still underlies essentially every processor, memory, and image sensor made today.
The "no static current" promise has frailties that dominate modern chips: as transistors shrank, leakage — current seeping through the thin gate oxide and across the channel even when a gate is off — made idle gates drip power, and the brief switching overlap (short-circuit current) adds up too. Together these forced the industry to chase power-saving tricks like clock gating, multiple threshold voltages, and FinFET transistors. CMOS was co-invented by Frank Wanlass at Fairchild in 1963 — decades before it became the default, back when its slower speed seemed a poor trade for the power savings.