In it I mentioned that cookies are a method by which Web servers both store and retrieve information on the browser, and I also explain how to configure your browser to accept or reject cookies. A protocol is a method by which two computers agree to communicate. As human beings, we use language as a protocol. For instance, in this article, written English is our protocol, or method of communication. Cookies are needed for many important Web applications, such as shopping carts, search engines, and Web-based electronic mail.
Persistence is achieved through cookies.
Persistence refers to transactions from a browser that must be processed by the same Web server to ensure the integrity of each transaction. Maintaining all items placed into a shopping cart or the actual credit card processing of the items in the shopping cart are examples of where persistence is required. Cookies are also used to identify each request. AOL is the classic example because they use proxy servers to access the Internet. Multiple users can enter a Web site with an identical IP address.