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.