The left button is the primary mouse button, and it used to perform common tasks like selecting menu commands, pulling down menus and double-clicking. A double-click is performed when the left mouse button is pressed twice in quick succession, usually about half a second. The double click is mostly used to open icon shortcuts on the desktop and other windows.
Pressing and holding down the left mouse button allows users to move items around the screen or highlight text. Dragging and dropping is mostly used to move folders and files to different locations. The same action is also applied when re-sizing objects.
The right button of the mouse is mostly used to open contextual menus. The scroll wheel is a different mouse button type that includes small wheel, which can be rotated to provide an input. It is mainly used to scroll up and down long documents. When used in conjunction with the Ctrl key, it can zoom in and out.
Other applications like video games may use the mouse buttons for other functions, like firing a weapon in a first-person shooter game. The mouse settings can be configures to suit personal needs and preferences. For example, left-handed users can change the main mouse button to the right button.