REST, or Representational State Transfer, is an architectural style for designing networked applications. It relies on a stateless, client-server communication model, where requests from clients are made to servers using standard HTTP methods like GET, POST, PUT, and DELETE. The core principles of REST include the use of resources, which are identified by URIs, and the representation of these resources in various formats such as JSON or XML. This approach allows for scalable and flexible web services that can be easily consumed by different clients, making it a popular choice for modern web development.