Definition of Terms:
A "cookie" is a small file that the site (server) requests your browser to store on your computer. It cannot be viewed by anyone other than the site that stored it.
When you view a web page, your computer (referred to as the "client" or "web browser") receives the page from a "web server" or "server". The software on your computer that allows you to view the page is called a web "browser".
When you visit a web site, certain information about the type of hardware you use, your browser, your geographic location, etc. is sent by your browser to that site's server. The site can choose to (a) not use or retain the information, (b) keep it on their server or (c) save it on your computer in a cookie. If you fill out a form, the information may be (a) discarded after it is used, (b) kept on their server or (c) saved on your computer in a cookie. If information is kept on your computer in a cookie, it is not available to them unless you visit their site again.
Cookies are an integral part of the web. They are information packets sent by a web server (the "server") to a web browser (the "client"), and they are stored on the client computer (your computer) by your browser software.
What is the purpose of a cookie?
A web site often needs to "remember" things about your visit to their site – things like which page you visited, what search term brought you to that page, what product you viewed, how long you viewed the page, your geographical location, etc. The cookie came about primarily to prevent the web site owner from having to allocate large amounts of disk space to save information about visits from all of its client visitors. The information is instead stored on each client's computer. This also provided to the site visitor (client) increased security and privacy since their data is not stored somewhere else. To learn more about cookies, visit AboutCookies.org or the wikipedia article "HTTP cookie".
If you are not using your own computer or are on a public computer, you might consider disabling cookies (see How to Control, Disable and Delete Cookies below).
How to Control, Disable or Delete Cookies
All modern browsers allow you to change your cookie settings. These settings will typically be found in the "Options" or "Preferences" menu of your browser. Some browsers allow anonymous browsing or the blocking of cookies on a site-by-site basis.
In order to understand these settings, see the References section below. You can also use the "Help" option in your browser.
Adverse results of blocking cookies:
Blocking or deleting cookies will negatively impact the usability of some websites.