This lecture covers the importance of System Modeling Languages such as OPM, SysML, and Modelica in modern Systems Engineering. It discusses the limitations of traditional document-based systems engineering and the transition to Model-based Systems Engineering (MBSE). The lecture explains the key features of System Modeling Languages, including ontology, semantics, and syntax. It also explores the Object-Process Methodology (OPM) and the wide applicability of SysML in various industries. The lecture concludes with insights into the field's current transition phase.