There a two kinds of cookies. Because a session cookie is never written to a drive, it is destroyed as soon as you close your browser. A persistent cookie is a more permanent line of text that gets saved by your browser to a file on your hard drive. Some cookies we use are persistent and some are session only. If you have your browser set to notify you before accepting cookies the notice will tell you if the cookie expires some time in the future or not.
Persistent cookies have an expiration date in the future.
Session cookies have no date associated with them. No other site can request it. When you return to this site, the cookie is sent back to the Web server, along with your new request. We use this information to create summary statistics which are used for web site planning and maintenance and to analyze system performance. This information tells us the number of visitors to the different sections of our site and helps us understand if our site is meeting the needs of our visitors.