A cookie is a small text file of letters and numbers that gets put onto your computer when you visit a website. This allows the site to distinguish you from other users.
A cookie isn't a computer program, can't read files on your computer, can't carry viruses and can't install malware onto your computer.
Most web browsers allow some control of most cookies through the browser settings. To find out more about cookies, including how to see what cookies have been set and how to manage and delete them, visit http://www.aboutcookies.org/ or http://www.alaboutcookies.org/.
Most browsers allow you to refuse to accept cookies.
Blocking cookies will have a negative impact upon the usability of some websites.