Mouse

It is an example for pointing device.
A ball is used underneath the mouse to detect the movements. This ball helps to control the pointer(cursor) on the screen.

                                                             Mechanical (Normal) Mouse


There are mainly two buttons on the mouse, they have different functions.
Very often left button is used for selection and right key for dropdown menus.

In optical mouse, the movement is detected by the reflection of light.

                                                                    Optical Mouse


In optical mouse, balls are not using. Hence, no moving parts are there.

                                                  Mechanical Mouse v/s Optical Mouse

Cordless mousses have no cord to connect with the system. It uses Bluetooth technology to establish the connection.

                                                                Wireless Mouse


Advantages;

It is  faster to select an item using mouse than using keyboard.
Mousses are smaller in size so takes less space only.

Disadvantages:

Easily damaged.
Without flat surface, it is difficult to use mouse.