The mouse is a peripheral device designed to help the user to better interact with the computer and its resources. The mouse is part of the computer hardware along with the keyboard provide the user the means to input data into the computer in the form of instructions.

The name mouse comes from the fact that early models (the ones that had a wire connecting it to the computer) resembled a real mouse. The connecting wire was interpreted as the tail of a real mouse.

The mouse is a pointing device that works by detecting two-dimensional motion relative to its supporting surface. More simply put it detects the up - down, left - right or any combination of these movements to move the arrow (known as a cursor) on your computer monitor in a similar fashion. The cursor on your computer monitor is a virtual representation of your physical mouse. The distance (measured in pixels) the arrow on the screen moves is directly related to the distance (measured in inches) of the mouse.

The early versions of the computer mouse consisted of only two buttons and a ball. One of the buttons (left one for right handed people; right one for left handed people) provides functions like selecting items on the desktop and initializing different applications. These mouse devices were mechanical because the ball of the mouse detected movement with the help of small wheels inside the mouse. One button mouse devices were available with the Macintosh up until late 2005 since the Macintosh user interface has most functions available with a single button mouse.

Newer version of the mouse device included a third button, replaced after a while with the scrolling wheel which also acts a button. Other buttons like the mouse double-click button, scrolling buttons and other buttons with different options are available with certain types of mouse devices. The type of additional buttons is usually based on the primary purpose of the mouse. The gaming mouse, for example, can have buttons that provide quick and easy access to a wide variety of useful functions in-game.

The mechanical mouse was replaced by the opto-mechanical mouse device which used optical sensors along with the mouse wheels to provide a better performance of the mouse device. Eventually these were replaced by the optical mouse that completely eliminated the mouse ball. The optical mouse uses a LED (light-emitting diode) and photodiodes (in other words it used a laser) to detect movement relative to the underlying surface instead of the mouse ball. These days the optical mouse is the most widely used.

Mouse devices that use a cord connect to the computer through a PS/2 or USB port. Some models no longer use a cord to connect to the computer. These are wireless mouse devices use infrared radiation (Infrared Data Association or IrDA for short) or radio waves (Bluetooth) to connect to the computer. However both of them are for short range data transmission. Bluetooth has higher data transmission range than IrDA.

Older models of the mouse which use a ball require a mouse pad for optimal performance. Mechanical mouse devices often get lint and dust stuck on their moving parts and require regular maintenance to ensure that it works as it should. The absence of a mouse pad doesn't represent a problem for the mouse devices that don't use a ball. The optical mouse can function properly on a multitude of surfaces because of its laser technology. Lint and dust are not a problem for the optical mouse since it doesn't have moving parts,

Optical mouse devices are usually designed to be power saving. This is especially true for wireless mouse devices which use batteries to function. To this end manufacturer have designed the LED or laser the mouse to dim or blink. Because of this function the life of the LED or laser is often increased. Some mouse devices designed for gaming don't have this function in order to reduce latency and to improve responsiveness.

The computer mouse was originally not sold together with computers. It was introduced only after computer manufacturers realized the success and functionality it had with the Macintosh.