Today this device is on virtually every computer. The primary function is to move the mouse pointer on the screen. The mouse pointer can be used for many actions on the computer. Clicking or double clicking an icon, folder, or other object will open a document or execute the program. Users can also move an icon, folder, or other object by clicking a mouse button and dragging the object with the mouse pointer. Pointing to an item on the screen means moving your mouse so the pointer appears to be touching the item. When you point to something, a small box often appears that describes the item.