What is a cookie? How are they used on Internet?

Question :

What is a cookie? How are they used on Internet?

 A cookie is information that a web site puts on our hard disk so that is can remember something about us at a later time. Typically, a cookie records your preferences when using a particular site. Using the web’s preferences when using a particular site. Using the Web’s Hypertext Transfer Protocol (HTTP), each request for a web page is independent of all other requests. For this reasons, the web page server has no memory of what pages it has send to a user previously or anything about our previous visits. A cookie is a mechanism that allows the server to store its own information about a user on the user’s own computer. We can view the cookies that have been stored on our hard disk. The location of the cookies depends on the browser. Internet explorer stores each cookie as a separate file under a Windows subdirectory. Cookies have been of concern for internet privacy, since they can be used for tracking the browsing of a user. HTTP cookies are used for user authentication, user tracking and maintaining User-specific third-party cookies also allows for tracking across multiple sites.