Mechanical Keyboard Terms
While 6KRO and NKRO are by far the most common levels of mechanical keyboard 'key rollover' functionality, there are still other numbers used. The number represents how many keys you can press at once and still have them be recognized by the keyboard. Most membrane keyboards are 2KRO and 3KRO. Some mechanical keyboards which aren't quite NKRO come in 20KRO flavors.
Currently, the most commonly seen 'Key Rollover' functionality of USB interfaced keyboards. 6KRO means you can push up to 6 keys + modifier keys (CTRL, ALT, etc.) at once and the keyboard will recognize all of your key presses. 6 keys is usually more than enough since most aren't usually mashing 7+ keys simultaneously, even with video games. However, if you do utilize 7+ keys at once, you can always get a keyboard with NKRO (no key rollover).
Activation Point (or Operating Position) is the key travel distance where the key is actually recognized by the keyboard. Actuation force is the force required at this point. Put simply, it's how hard you have to press the key for it to be recognized.
Bottoming out is pushing a switch all the way down. Linear switches like Cherry MX Blacks and Cherry MX Reds require you to push the key all the way down (bottom out) to register the key press.
See "Key Bounce"
'Click' is the noise made by the switch when activated and 'Clack' is the noise made when it bottoms out.
Clicky switches make an audible 'click' when typing. Clicky switches are typically preferred by typists, but are noticeably louder than other mechanical switches. Use with caution near noise sensitive co-workers or spouses :)
Some keyboards have approximately the same number of keys as a fullsize keyboard but are laid out in a different way to reduce width.
Hitting the same key in rapid succession. See also 'Triple Tap'. Most commonly used in video games.