UML Diagrams, or Unified Modeling Language Diagrams, are visual representations used in software engineering to illustrate the design and architecture of a system. They help developers and stakeholders understand how different components interact and function together. UML provides a standardized way to visualize system components, making it easier to communicate ideas and requirements. There are several types of UML diagrams, including Class Diagrams, Use Case Diagrams, and Sequence Diagrams. Each type serves a specific purpose, such as showing the structure of a system, detailing user interactions, or illustrating the flow of messages between objects. These diagrams are essential tools for effective software development and project management.