Rational Rose is a visual modeling tool that allows users to graphically represent different views of a software system using diagrams. The document introduces various diagram types in Rational Rose, including use case diagrams, class diagrams, sequence diagrams, collaboration diagrams, activity diagrams, component diagrams, deployment diagrams, and statechart diagrams. Each diagram type shows a different perspective and can be used at different stages of the software development process to help with requirements, design, and communication.