What exactly is a context?

There is something that is kind of messing me up... I do not exactly understand what a "context" is... I am starting to read J2EE material, and there are all kinds of context objects, usually associated with some other kind of object.
What exactly is the context object in relation to the other object?
Thanks,
PM

Have a look at the API.
Example:
public interface SessionContext
extends EJBContext
The SessionContext interface provides access to the runtime session context that the container provides for a session enterprise Bean instance. The container passes the SessionContext interface to an instance after the instance has been created. The session context remains associated with the instance for the lifetime of the instance.
Or...
public interface ServletContext
Defines a set of methods that a servlet uses to communicate with its servlet container, for example, to get the MIME type of a file, dispatch requests, or write to a log file.
There is one context per "web application" per Java Virtual Machine. (A "web application" is a collection of servlets and content installed under a specific subset of the server's URL namespace such as /catalog and possibly installed via a .war file.)

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