As with all retailing and marketing, the ability to track a person's use of a website provides very desirable information for the web designers and retail analysts. It can not only indicate how easy the site is to use, but also what types of people are browsing the site, and what other sites they are interested in. In marketing, information is a valuable commodity.

For this reason, it's probable that as you have browsed your way through websites, your clicks and choices have been monitored, and your preferences noted. Often, to make sure they gather data that is only from a single individual, they'll install a cookie on your computer with a unique code, which they attach to any browsing records they compile about you.

You may even have downloaded useful additions to your operating system, perhaps fun elements such as novel cursors or smileys for your email. Many of these “free” programs have embedded in them some monitoring software, that sends back details of your browsing habits, or worse, your mouse clicks and keyboard input (these are known as keyloggers).

To combat these threats to your privacy, you can download software to search out these cookies and programs on your hard disk, and quarantine them or delete them.