An analogy would be to think of a cookie as a valet parking service. You receive a ticket, and the attendant parks your car. When you later return with the ticket, the attendant uses it to locate your car and return it to you. Cookies give Network Managers or Webmasters the power to customize their sites on an individual basis. Cookies can help personalize information, or help with on-line sales.
Cookies also provide the means to keep the site content applicable to a customer's interest.
In short, cookies can store database information, custom page settings, or almost anything that makes a site individual and customizable. Obviously, the cookie, and the information it contains, can help a company offer differentiated services to their customers. The BIG-IP Controller, a high availability load balancing product, offers Cookie Persistence. This method of persistence uses an HTTP cookie stored on the customer's computer to allow the customer to reconnect to the same server previously visited at a web site. Some BIG-IP Controller models also feature cookie persistence with the hash option.