Mouse

The humble mouse it has changed slightly over the years but still does the same thing, providing a method for navigating around a desktop/program quickly and easily. Originally it was just a trackball (The ball moving along a surface thus turning shafts in the mouse which was detected by sensors built into the mouse.) which has later evolved into an optical system where a small camera takes photos of the surface many times a second which it uses to determine movement.

Basic Mouse Terminology

The latest mice on the market have multiple extra features. Some are listed below.

4-Way Scrolling / Tilt Wheel - The scroll wheel tilts from side to side to allow horizontal scrolling.
Customisable Buttons - Various buttons on the sides and top of the mouse which can be customised by the user to launch applications or perform other tasks.
DPI - Dots Per Inch, the higher this number the more accurate the mouse will be.

Manufacturer-Specific Terminology

Application Switch Button (Logitech) - Although missing from their latest mice and placed in a somewhat awkward position in the mice that it is included on, the Application Switch Button is in essence a one-button Alt+Tab key combo.