What are Cookies?

At last you stood up and ordered that ONE+ mobile phone from Amazon. The next time you went there, Amazon site not only greeted you by your name "Hi, Zen!" but also suggested you some accessories which were related to the phone- Cases, covers, SD cards and all. How did the site know? Is it reading your mind? Or the site can make some intuition! Not exactly. Welcome to the world of cookies.

A cookie is a tiny file that a web server stores on your machine. Its purpose is to allow a web server to personalize a web page, serving as a small record of your personal preferences that the server can access. When you ordered that phone, the server set a cookie on your machine that recorded your name and previous purchases; when you returned to Amazon, it simply read the cookie and reconfigured its page to say, "Hi, Zen!" and to suggest items that you were likely to buy based on what it read in the cookie.

Much has been written about whether cookies create a security or privacy hazard for you. If your browser is working properly, the security hazard is minimal. It is, at first glance, unsettling to think that web servers are storing information on your hard drive without your knowledge - but cookies aren't executable programs. They can't search for and accumulate information from elsewhere on your system. They simply record information that you have already given to (or gotten from) a web server.

Cookies do make it easier for advertising companies to gather information about your browsing habits. For example, a company that advertises on web sites can use cookies to keep track of where you have seen its ads before and which ads you clicked. Advertising agencies are coming up with slimier and more efficient ways of tracking your movements all the time.
For example, in 2000, the ad company DoubleClick used cookies to invisibly track all sites users were surfing to - along with their names, street addresses, and e-mail addresses, which would be stored in a large database used for targeted advertising. The only way to avoid being tracked by this program was either to disable cookies from DoubleClick or to go to DoubleClick's web site and specifically opt out. They never signed up for DoubleClick's tracking program, so most people were unaware that their web surfing habits were being cataloged and thus never knew to opt out.