A cookie is a small text file that is stored on your computer when you visit a website.  It can contain information about how to customize the appearance of a website interface for your user account, the contents of your shopping cart, or even information about a browsing session.  Cookies consist of a variable name-value pare. For example, “ID=65498976″.  A company such as Ebay might use this string of information to identify you once you’ve logged in.  The ID value of the cookie can then be used to serve up a webpage configured according to your preferences–e.g., a certain color, certain account settings, etc.

Contrary to popular belief, cookies are not viruses or spyware.  They are simply files that serve a useful purpose, whether it be enhancing the user’s experience by ‘remembering’ certain preferences or serving up ads that are more consistent with a user’s web surfing patterns. They are not computer programs.  They do not execute any code.  They can also be used to track which pages your visit within a website for statistical purposes. They will not read and transmit any personal information from your computer’s hard disk to anyone.  They will not harm you computer in any way.

What about third-party cookies?  Third-party cookies are cookies that are sent to your computer from a website that resides outside the domain of the website you are visiting.  There may be networks of participating websites.  Whenever you visit a participating website the cookies on your computer are transmitted to the host servers and information about which websites and pages you have visited is received.  The cookies can then be modified and re-sent to your computer for future use.  The banner ads that are served up on these websites are taylored toward your cookies.  For example, if your cookies show that you have visited several sports related sites, then ads for sports related products or services may be served on the webpage rather than ads for makeup or gardening.

Most web browsers allow users to black third-party cookies by setting the browser preferences.  If you feel uncomfortable with the build-up of cookies that have accumulated on your hard disk you can delete them at any time.  But when doing so, realize that you may be deleting your user preferences for a particular account.  For example, you might be asked to reset your account preferences the next time you log into Amazon.