Sensitivities

Finding Your Sensitivity
There isn't one perfect sensitivity. The goal should be to find the sensitivity that is right for you. The most popular way to do that is to just fiddle with the sensitivity slider until it "feels good". One of our most skilled players recommends a sensitivity such that dragging your mouse all the way across your mousepad results in a perfect 360 in game. A more calculated approach to finding your perfect sensitivity can be found in this video.

Conversions
Unfortunately, mouse sensitivity isn't standardized across games. There's a site, mouse-sensitivity, that will allow you to convert one game's sensitivity settings into approximately equivalent settings in another game. There is also a tool, KovaaK's sensitivity matcher, which will allow you to manually determine and test sensitivities between games (how?).

CPI, or counts per inch, is a measurement of how many units of movement the mouse will report if you move it one inch. DPI, dots per inch, is an often used alternate acronym stolen from printer resolutions meaning the same thing in this context.

Polling rate is a measure of how often the mouse hardware reports changes to the PC.

cm/360 is the physical distance across one's mousepad that the mouse must travel in order to execute a perfect 360 turn in game.

Acceleration
There are 4 types of acceleration: none, linear, exponential, and stepwise. Really though, all you're doing is messing