The architecture of the authorization system is based upon the utilization of several individuals but related logical components: Profiles, Objects, Fields, and Authorizations.
The user ID refers exclusively to profiles. Each profile grants a set of specific system access authorizations to user.
The hierarchical authorization concept in SAP.
Composite Profiles
Composite profiles refer to the various employee roles available in the corporation (for instance: Purchasing / Receiving Clerk or Accounts Agent). As the name suggests, composite profiles may contain multiple user IDs necessary to perform all the business operations associated with a particular role. A composite profile may encapsulate another composite profile(s).
In practice, a model composite profile should be recognized for each possible role in the organization, which may be used to produce hybrid composite profiles. The over existence of the hybrids can defy the very purpose of composite profiles and they should be created only when specific needs arise.
User Ids
User ids allow access to SAP applications. Each user must have a corresponding profile specifically assigned. In many situations, multiple composite profiles can be assigned to a user ID, depending on the role(s) an individual user is responsible for, in the business processes.
Authorizations
Authorizations are the key building blocks of SAP security. Authorization is the process of assigning values to fields present in authorization objects.
In SAP, access to all system functionality is achieved through a complex array of authorizations. Sometimes users find that they lack the necessary authorizations to perform a certain function in the system, in which case the message: "You are not authorized..." is displayed at the bottom of the screen.
An authorization process may ask for second associated authorization process which in turn asks for third and so on. For example, the task of paying a vendor invoice may require 10 different authorizations.
