Introduction
A cookie is a small data file stored by websites in order to make use of a web page faster. This is done through the web, through the saved data file, can recognize your computer when you visit the site next time. A cookie is not harmful to your computer.
What are cookies?
A cookie is a small text file that a website saves on your computer or mobile device when you visit the site. It enables the website to remember your actions and preferences (such as login, language, font size, and other display preferences) over a period of time, so you don’t have to keep re-entering them whenever you come back to the site or browse from one page to another.
How to control cookies
You can control and/or delete cookies as you wish – for details, see here. You can delete all cookies that are already on your computer and you can set most browsers to prevent them from being placed. If you do this, however, you may have to manually adjust some preferences every time you visit a site and some services and functionalities may not work.
Additional Information
http://ec.europa.eu/ipg/basics/legal/cookies/index_en.htm
Wikipedia Definition
http://en.wikipedia.org/wiki/HTTP_cookie