Cookies are tiny text files that are transferred in user's computer. They are two types, permanent and session cookies:
Permanent cookies remain in your hard disk after you finish your visit keeping information that will be used once you visit, our site next time.
Session cookies are used to recognize that you have entered inside the website, without having to be asked for information such as username and password each time you want to complete a transaction. These are automatically erased once you logoff and leave the website.
Cookies does not harm user's computers and their files.
The Help feature on most browsers will tell you how to prevent your browser from accepting new cookies, how to have the browser notify you when you receive a new cookie and how to disable cookies altogether. Additionally, you can disable or delete similar data used by browser add-ons, such as Flash cookies, by changing the add-on's settings or visiting the website of its manufacturer.