REST (Representational State Transfer) is an architectural style for designing networked applications. The core principles are:

• Stateless: Each request contains all information needed to process it
• Client-Server: Separation of concerns between client and server
• Cacheable: Responses should be cacheable when appropriate
• Uniform Interface: Consistent way to interact with resources
• Layered System: Architecture can be composed of hierarchical layers
• Code on Demand (optional): Server can send executable code to client

REST uses resources identified by URIs and standard HTTP methods to perform operations.