What are cookies?
Cookies are information capsules, used to identify you, and not the computer. When you log on to a website, using for instance username and password, you are sent a cookie that “tags" you as who you are. It is then stored on your computer for later use.
Later on, when the website needs to show you customised or personalised information, it retrieves the cookie, thus knowing that you are indeed the person for which the information is intended.
Today, cookies are used on all popular sites, and some of the information gathered using cookies could be used for marketing purposes. As a rule of thumb, you should allow cookies from sites that you are familiar with, such as your on-line bank or search engines.