Threshold voltage (Vt)
Beginner
How hard the electricity must push before one of the chip’s tiny switches turns on.
Novice
The control voltage at which a transistor switch starts to conduct strongly. A lower threshold makes switching faster but lets more current leak when the switch is off; chip libraries offer several threshold flavors to choose between.
Expert
Sets the floor for the supply voltage: speed collapses as the supply approaches it. Below threshold, current falls by roughly a factor of ten for every 60–100 mV (the subthreshold slope), so every 100 mV taken off the threshold costs roughly ten times more off-state leakage.