A mouse is a handheld input device that enables users to interact with a computer by controlling a cursor on the screen. Typically, it has two or more buttons used for various commands like clicking, selecting, or dragging items, along with a scroll wheel for navigating vertically through pages or documents. The mouse can connect to a computer via USB (wired) or Bluetooth (wireless), and it operates through sensors, which detect motion either through a laser, optical sensor, or a ball in older models.