An architecture expresses a fundamental structural organization schema for software systems. It provides a set of predefined subsystems, specifies their responsibilities, and includes rules and guidelines for organizing the relationships between them.

* Object-Oriented/Abstract Data Style

* Layered Hierarchies

* Blackboard architecture

- involving shared access to data with loosely coupled agents

* Client/Server

* Three tier Client/Server architectures

* Peer-to-Peer Architecture