What are cookies and what are they for?
A cookie is a small piece of text that usually has an anonymous unique identifier. When you visit a website, their computer asks your computer for permission to store this file on your hard drive in a specially reserved place just for cookies. As you move from page to page on their site, it knows that this is the same person.
Cookies for adverts
These cookies are set by the advertiser, so I have no control over them. They are mainly used to show adverts that are relevant to you and limit the number of times you see the same advert. They can also be used to measure the effectiveness of advertising campaigns as you would expect.
Cookies that save your settings
When you fill in a form, cookies remember so you don't have to type it in each time you return. They remember changes to text size, font and other things you may customise, so it's always the same when you visit other pages on their site.
Clearing your cookies
Cookies can be permanently deleted from your hard drive, usually by deleting your history. In some browsers, you can set it to delete cookies when you close the browser. See your browser's Help section on how to do this.