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## Pointing Devices Pointing devices are used by graphical operating systems such as Windows to show the motion of a pointer or cursor, and to enable the user to control and select objects on the display. ### The Mouse The mouse is a pointing device that a user operates by moving over a flat surfac...

## Pointing Devices Pointing devices are used by graphical operating systems such as Windows to show the motion of a pointer or cursor, and to enable the user to control and select objects on the display. ### The Mouse The mouse is a pointing device that a user operates by moving over a flat surface. This movement is mirrored by a pointer on the monitor screen. On the top of the mouse are two buttons that allow you to make selections on your screen, move objects around the screen, and paint or draw. These buttons have the following uses: * **Clicking:** This involves pressing and releasing the left mouse button quickly. This is often used to select a pull-down menu in a program or an item on the screen. * **Double clicking:** This involves pressing and releasing the left mouse button twice. This is often used to open a document, a graphic or a program. * **Dragging and dropping:** This involves placing the pointer over an item on the screen and clicking and holding down the left mouse button. While holding down the left button, you can move (drag) the object (file or icon) to another location on the screen. When you release the button, the object remains in its new location. This is often used when copying a document to USB storage or hard disk. * **Right clicking:** This involves pressing the right mouse button, which displays a list of commands on the screen, depending on which program you are using at the time. By moving the pointer, you can select one of these individual commands, which will perform a specific action. In addition to a regular mouse, you can also choose from other options, with some based on your personal preference and others designed for comfort. We look at some of these options below. ### The Optical Mouse The optical mouse can slide over most surfaces as it does not have a ball. It emits a small beam of red light that bounces off the surface into a sensor. The sensor sends coordinates to the computer, which in turn moves the cursor or pointer on the monitor screen, according to these coordinates. A mouse can be wired (attached to the computer by a USB cable) or wireless (connected by radio-frequency (RF) technology). ### The Trackball Mouse The trackball mouse has a large ball on top rather than underneath, which you roll with the palm of your hand or fingers. This type of mouse is not as precise as a regular mouse for some actions, but people who suffer from repetitive strain injuries may find them more comfortable to use. Figure 2.6 shows a thumb-operated trackball mouse.