Mechanical mouse switch
Also called micro switch · Omron switch
A mechanical mouse switch closes two metal contacts when you click. They are rated in millions of clicks but wear and oxidation make them bounce long before that rating in many cases.
In practice
Most mice still use mechanical switches because they are cheap and feel crisp. The click rating printed on the box measures when the switch stops clicking, not when it starts to bounce. Real wear depends on how hard and how often you click, so a heavy gamer can wear out a switch in a year that would last an office user many more.
How to check
The mouse test catches the result of wear: double clicks under 50ms and drops while holding. To find out whether your mouse uses mechanical switches, check its product page or a teardown. If a mouse with mechanical switches starts chattering out of warranty, replacing the switch is a well documented soldering repair.