Basically, cookies can store tracking data about your browsing, but cannot access any personal information from your browser. A summary of cookie capabilities is given below:
- Default settings. If you have already entered data to a web site voluntarily, then cookies can store it and later retrieve it to set default settings every time you visit, such as user name, password, Internet preference settings, etc.
- Custom content. If you search for words on a site associated with a certain subject, such as “garden”, the site could learn to present you with more information on gardening related subjects in side-bars and related links sections.
- Form data. Cookies can be used by browsers and web sites to archive information that you enter on complex forms, so that if you leave the page or you become disconnected and come back to the page later, your previously entered data can be preloaded for you.
- Limitations. Cookies cannot access your email address, read files from your hard drive, or obtain your credit card numbers or other personal information. Cookies cannot put viruses on your computer, because they are text data files and not active programs.
- Cross-site access. Cookies from one site cannot be used to record your activity on other sites, and a site cannot read another site’s cookies. Other than site activity a cookie cannot access any other information with two exceptions: a site can record the address of the page you linked from, and it can record the address of the page you jump to (if the links are customized to transmit the data).
The Cookie Demo site provides a demonstration of cookies in action.