The user context is the data that is specifically assigned to an SAP user.
Whenever an SAP user starts a transaction (an ABAP program), the work process processing the request always requires the user context.
Each user can open up to six external sessions (System ® Create session).
The user context contains a user-specific area containing user and authorization data, and a session context for eachSAP session.
Each external session can administrate from its side several internal sessions (indicated here with IS), that will not be explained in further detail here.
All user contexts are contained in a common resource (SAP Extended Memory, SAP Roll Area), which enables a fast context change.