A computer mouse is an input device that allows the user to move a cursor on the screen and make selections using the cursor. In Microsoft Windows, the mouse and cursor are used to interact with the desktop, taskbar, windows, and programs.

Only one computer mouse and cursor can be used per instance of Windows. In most laptop computers, a built-in touchpad serves the purpose of controlling the cursor instead of a mouse.

Layout

Computer mice have a base that detects movement in two dimensions: horizontal and vertical. Any degree of movement in either of the two directions will result in a slightly different input.

Most computer mice have three parts, which are on the end of the mouse that is meant to face the computer screen. Two of these are a pair of identical buttons, being large and occupying half of the mouse's top surface. These are the left and right buttons. Pressing down on one of these buttons is called "clicking".

The third part (if it is present) is called a scroll wheel. It is a small wheel situated between the two larger buttons. The scroll wheel can be pressed, acting as a third button. The scroll wheel can also be pushed or pulled along its top; pushing the wheel sends an "up" input, while pulling it sends a "down" input.

Function

Dragging the mouse in a certain direction across a surface will move the cursor in the corresponding direction.

The left and right buttons are used for making selections on an item that the cursor is overlaying. There are different kinds of selections:

• The primary selection is used to directly select an item. By default, it is activated using the left button. The primary selection is commonly called a "left click" for this reason.
• The secondary selection is used to access additional options pertaining to the item that was selected. By default, it is activated using the right button. The secondary selection is commonly called a "right click" for this reason.
• When a primary selection is made twice in quick succession, the mouse sends a distinct input called a "double click". It makes Windows perform the default action associated with the selected item.
• When the button associated with a primary selection is held down whilst the mouse is dragged, the selection is moved alongside the cursor.

When the scroll wheel is rolled while Windows is focused on a program with a menu that is not fully displayed, the menu shows items below or above the items that were being displayed before. When the scroll wheel is pressed, it sends a "middle click". Holding down the middle click while dragging the mouse vertically causes a program with a long menu to automatically scroll in that direction.