A web service is a collection of open protocols and standards used for exchanging data between applications or systems. Software applications written in various programming languages and running on various platforms can use web services to exchange data over computer networks such as the Internet in a manner similar to inter-process communication on a single computer. This interoperability (e.g., between Java and Python, or Windows and Linux applications) is due to the use of open standards.
Web services based on REST Architecture are known as RESTful Web Services. These web services use HTTP methods to implement the concept of REST architecture. A RESTful web service usually defines a URI (Uniform Resource Identifier), which is a service that provides resource representation such as JSON and a set of HTTP methods.
All REST testing capabilities of SoapUI are based on a logical representation known as REST service. We should not confuse this with the term "service" here, since it is not a service implementation but a mapping of the RESTful service that is being invoked. We can add as many REST Services as we can in a SoapUI project. Each represents a particular RESTful service. They are as follows −