A cookie is a small file which asks permission to be placed on your computer's hard drive. Once you agree, the file is added and the cookie helps analyse web traffic or lets you know when you visit a particular site.
I use traffic log cookies to identify which pages are being used. This helps me analyse data about web page traffic and improve the website in order to tailor it to customer needs. I only use this information for statistical analysis purposes. Your IP address is anonymised in this process therefore you can't be individually identifiable.