Computer mouse is considered to be an essential part of PC and are usually supplied with desktops. If you are using laptop then touchpad can be used instead of a mouse. However, there are many users who prefer mouse than using touchpad.
As defined in Wikipedia a mouse is “In computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons. It sometimes features other elements, such as "wheels", which allow the user to perform various system-dependent operations, or extra buttons or features that can add more control or dimensional input. The mouse's motion typically translates into the motion of a cursor on a display, which allows for fine control of a graphical user interface.

Mouse was first designed in 1950s, patented in 1960s and was used in limited scale in 1970s. The use of mouse became popular in 1980s when Xerox and later Apple included mouse as one of the shipped items with their computers.
There are different types of computer mouse. We have jotted down the major types here.

Types of Mouse:

A. Movement Based Sensing Device

Mechanical Mouse: The oldest but still the most common mouse design is the classic "mouse ball" design. This type of mouse contains a small ball and two rollers inside the mouse which sense the horizontal and vertical movement of the ball on a surface and send the signal to the computer system for corresponding movement of the cursor.

Optical mouse: It uses optical technology where the movement of mouse over a grid surface is read through signal emitted by LED (red color) located inside the mouse and then the data is transferred to the computer for corresponding movement of the cursor. So it does not require any moving parts. Optical mouse has many advantages over the mechanical ones like smoother response less wear and tear etc. This is the most common type mouse in use because of its increased tracking resolution.

Laser Mouse: This also works in the same principle as optical mouse except that it uses laser instead of visual (red) right. This type of mouse is more efficient than the optical one.

There are other types of mouse but they are not commonly used.

B. Types based on method of communication between computer and mouse

• Connection through wire - common type
• Wireless mouse - fast replacing the common type i.e. wired one

C. Types based on Connectivity with Computer

• Through USB
• Through PS/2

How to select a computer mouse?

Before buying a mouse take into considerations factors like – your requirements, hours of use, availability of ports in computer. If you are a computer professional then consider the one which reduces the strain of repetitive computer work. It is better to go for a mouse which has better control over the movement of the cursor so that repetitive work is minimized Mouse is not an expensive equipment (in comparison to the price of the computer) so budget may not be constraining factor.