What notations do you know? What have you used in your work?

Among the well-known notations for systems analysis and modeling, the following can be distinguished:

• UML (Unified Modeling Language) — a universal modeling language, includes class diagrams, sequence diagrams, state diagrams, and others.
• BPMN (Business Process Model and Notation) — for modeling business processes.
• ER diagrams (Entity-Relationship) — for modeling data and their relationships.
• DFD (Data Flow Diagram) — diagrams of data flows.

In practice, UML is most often used to describe the structure and behavior of the system, as well as BPMN for visualizing and optimizing business processes.