flip-flop
A flip-flop is a tiny circuit that remembers a single bit — a 0 or a 1 — and holds onto it until you tell it to change. Think of it like a light switch that stays flipped: once you set it, it sits there keeping its position even after your hand leaves, until someone deliberately flips it again. That stubborn "staying put" is the whole point. Without it, a chip would forget everything the instant the current settled.
Most flip-flops only change at one sharp moment: the rising edge of a clock tick, like a camera shutter snapping a photo of the input at exactly that instant and freezing it. Line up a row of them and you get a register that stores a whole number; pile up millions and you get the memory and state inside a processor. Every counter, every CPU register, every bit your computer "holds in mind" rests on these little one-bit keepers.
The odd name comes from the way an early version could be "flipped" to 1 and "flopped" back to 0. People often mix up the latch and the flip-flop: a latch follows its input the whole time the clock is held open, while an edge-triggered flip-flop grabs the value only at the exact tick of the clock and ignores everything in between.