Someone asked about N.O. and N.C. contacts on a microswitch
A watcher of my 16N.1.3 Debouncing a Switch with a Set Reset Flip Flop video was confused by the switch having both Normally Open (N.O.) and Normally Closed (N.C.) contacts. He was used to pushbutton switches which are usually only N.O. Indeed, most pushbutton switches are Single Pole, Single Throw (SPST) with two contacts and a shorting bar that is held open by a spring so the contacts are open circuit, and then the contacts are shorted together when the user presses the pushbutton. (There are N.C. pushbutton switches and pushbuttons with multiple contacts, either SPDT or DPST but they are less common.)
Microswitches (miniature snap-action switches), on the other hand, are usually (almost always?) SPDT with a common terminal and both a N.O. terminal and a N.C. terminal. See Figure 16L.6 in LAoE or watch the video referenced in Footnote 7 on that page that has a visualization of how a microswitch works and shows the reason we use it for the switch bounce demonstration.
Microswitches often include a lever arm to reduce the actuation force and are typically used as mechanical limit switches; they are rarely human actuated like a SPST pushbutton switch.
Image courtesy of Benjamin D. Esham
The SPST microswitches that I have seen are actually SPDT switches with the N.C. terminal missing or cut off.
See https://en.wikipedia.org/wiki/Miniature_snap-action_switch for more information.