REST is an internet-based protocol for retrieving and updating information. It is the de facto standard for Cloud / Mobile server access. In the context of database access, a REST server responds to REST requests by making SQL and/or service calls to other REST servers, with enforcement of logic for security and integrity.
REST is a very good example of an Service Oriented Architecture. It is language/architecture neutral (works with C#, Java, Ruby. PHP etc), and is therefore often used as the basis for Enterprise Application Integration.
REST calls are well-conceived for performance, able to deliver large amounts of desired data in a single transmission (so-called "coarse grained access").
REST calls are simply HTTP calls. Since virtually every language provides HTTP support, such languages therefore support REST.
REST calls (requests) consist of a URL, a Verb and a Request Body. In the context of database information, we can summarize this as follows:
In the context of Espresso Logic, the REST Lab provides an easy way for you to experiment with your REST server, without writing a program.