Have you ever heard of Web Cookies? These aren't quite like the cookies grandma used to make. The term “cookies,” in a technical sense, refers to the files that websites use to track who visits their websites, and what they do while there. While this initially sounds like a huge invasion of privacy, there is really nothing bad about cookies.
Companies for years have used various ways to find out what their customers do when shopping their stores. When the hunter in your family gets a catalog from a sporting goods store, how did they know he would be interested in it? By keeping records of who bought what, stores can target their customers more efficiently. They often share that information with other companies who might try to sell you something. While this results in vast amounts of junk mail, stores can generally profit a great deal by keeping track of your purchases.
In the same way, cookies are used by websites to track what ads you click, what you answer when prompted by a question, or what your preferences are. With cookies, this is completely anonymous. The websites do not have a way of getting information about who you are, so they simply assign you a randomly generated "user ID", which will be placed in a cookie file. The next time you visit that website it recognizes that you've been there before and gives you customized features based on your previous visit. For example, when you visit http://www.google.com/, you are assigned a cookie the first time you're there. The website has features that allow you to customize your experience with the website with things like language, filtering, number of results per page, and more. If you set these preferences, the next time you come back to that site, you will have the same preferences set without having to reselect your options.
For each website you visit that uses cookies, one file will be created. The file is a text file that rarely is more than 1kb, which is quite small. Each file name contains the website address. While the contents of the file may seem like gibberish, the folks who created the cookie have a way of using this information to determine where you went and what you did while on their site. They can then get an idea of what's being used the most, how many new, unique visitors a page gets, etc.
Fortunately, when a website creates a cookie, that website is the only website that can access the file. Many rumors about cookies say that they can be destructive, or can allow unauthorized access to your hard drive. These rumors are false. A cookie is simply a text file, and is written to your hard drive by your own web browser as it's instructed by a website, so the website itself is not writing to your system.
