Rest(Representational State Transfer) is recommended style/suggested pattern which is recommend for web applications.
A System which is Restful is expected to meet the five principles listed below :
1.System must be represented as resource.
2.Uniform Interface (Usage of GET,POST,PUT,DELETE ) is advised to be used across the system.
3. Identify Resource by a Unique Identifier.
4. Communication via Representation (represent data by JSON/XML etc..)