Vertical Mouse:
Invented by Jack Lo in 1994, a vertical mouse is an alternative to a traditional computer mouse. For ergonomic purposes, vertical mice have the buttons and the scroll wheel rotated 90-degrees clockwise (or counter-clockwise for left-handed users). This requires the user to operate the mouse with their palm facing to the side, rather than facing downward.
Variants of the vertical mouse include different options for thumb placement. Some include a groove for the user to rest their thumb, while others include trackballs to move the cursor without physically moving the mouse.
Trackball Mouse:
A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down mouse with an exposed protruding ball. The trackball's buttons may be situated to that of a mouse or to a unique style that suits the user.
Optical mouse:
A mouse that uses light to detect movement. Introduced in the late 1990s, optical mice superseded mechanical mice because their sealed bottom surfaces do not absorb dust and dirt. They work by emitting light from an LED or laser, and a CMOS sensor detects the light reflections as the mouse is moved.
