During the use of a product, a session or connection is a execution context that
In other word, a session represents a sequence of action that an application can use to maintain authentication state of a user.
A session can last:
To keep track of the action in a session, an application uses a session token, which is a unique string, generally a nonce.
It's physically stored in a record and known as the session id for session identifier
The session id can be then passed between request. See web
The primary usage of a session is to hold the navigation context data.
It's also a mechanism to trace navigation against an application.
A session on a analytical level is a group of user interactions that take place within a given time frame. See User Analytics - Session (Visit)
A session has a validity mechanism. The most known is that after a period of time of inactivity, the session becomes invalid and is deleted by a garbage mechanism.
You will find this concept in all OSI layer
In the web, the session identifier is stored:
When the server receives an HTTP request, the server will look up the session information (user, connection time) using the session identifier as a key.
When you are making a connection with a database, you are just creating a session.
The session/connection information are stored in a table.
Connection are shared resource and therefore can not be a component of a release.