System Modeling Language
SysML is based on the Unified Modeling Language (UML), a de facto standard for software engineering developed within the Object Modeling Group (OMG) consortium. SysML was developed as a response to the request for proposal (RFP) issued by the OMG in March 2003. The development team includes representatives from more than ten companies. IBM has played a leadership role in the definition of the SysML standard by authoring part of the specification.
Figure 1: Comparison of SysML 1.0 with UML 2.0
The text in Figure 1 summarizes the various diagrams available in SysML. Requirements, Parametrics, and Allocations are new diagrams not available in UML. Activity and Block diagrams are reused from UML 2.0 and extended in SysML. Lastly, state machines, interactions, and use cases are reused from UML 2.0 without modification.
SysML is a modeling language for representing systems and product architectures, as well as their behavior and functionality. It builds on the experience gained in the software engineering discipline of building software architectures in UML (think of the classic Class diagram.) The architecture SysML describes represents the elements realizing the functional aspect of the system. The physical aspect is sometimes represented, too; for example, when the architecture represents how the software is deployed on a set of computing resources. - cited from IBM