Clicking involves pressing one of the two (three with most computer mice made these days) buttons.
The two typical buttons are the right and left buttons. The left mouse button is used to "activate" or "run" executable files and to select options from a menu. The right mouse button is used to bring up additional menus for items.
The scroll wheel can be found between these two buttons. The scroll wheel allows for page navigation.
There are different kinds of computer mice. The mechanical mouse is an older version of the mouse that consists of a ball and rollers. Now, laser is standard for computer mice. However, the laser mouse can be both wired and wireless.