session

In the computing world, a session refers to a limited time of communication between two systems. Some sessions involve a client and a server, while other sessions involve two personal computers.

A common type of client/server session is a Web or HTTP session. An HTTP session is initiated by a Web browser each time you visit a website. While each page visit constitutes an individual session, the term is often used to describe the entire time you spend on the website. For example, when you purchase an item on an ecommerce website, the entire process may be described as a session, even though you navigated through several different pages.

In some cases, a session is user-initiated. For example, the timeframe for an interaction between two personal computers used in online chatting or messaging is considered a session. The individual users initiate it, and ends it when it is finished.

Other kinds of sessions are initiated by technology. One of the most common is a client/server session between a server and a personal computer or other device or system accessing that server. Developers and others have developed session protocols for handling these interactions between systems. These cover all of the many interactions required for browsing the Internet, as well as sending and receiving email through various email clients. It is interesting to note that many of these sessions are actively hidden from the end users; in other words, the common user does not recognize that these sessions are occurring, and does not know much about what happens during these sessions. Analysis of technology-initiated sessions is largely the province of network administrators, security experts and others with a close knowledge of an interactive network.

Another example of a client/server session is an email or SMTP session. Whenever you check your email with an email client, such as Microsoft Outlook or Apple Mail, you initiate an SMTP session. This involves sending your account information to the mail server, checking for new messages, and downloading the messages from the server. Once the messages have been downloaded, the session is complete.

An example of a session between two personal computers is an online chat, or instant messaging session. This type of session involves two computers, but neither system is considered a server or client.