The REST stands for Representational State Transfer. It is an architectural style. It is not a protocol like SOAP. More details.
RESTful web services are an architectural style for designing networked applications. It stands for Representational State Transfer (REST), and it emphasizes statelessness, scalability, and the uniform interface between components. In RESTful web services, resources are identified by unique URIs, and interactions with these resources are typically performed using HTTP methods such as GET, POST, PUT, DELETE, etc. Data is exchanged primarily in formats like JSON or XML. This approach allows for loose coupling between clients and servers, making systems easier to maintain and scale.