With REST we cannot truly define a degree of understanding. Such a definition would assume that multiple people know and agree on what would be the full extent of that understanding. The problem with REST is not the different <i>amount</i> of knowledge that people possess, but the different <i>ideas</i> that they have about REST. Which is another way to say that REST is not really a well defined protocol. (Have you seen similar vague posts titled &quot;What IMAP4 actually means&quot;?)<p>Because it is not a well defined protocol, you cannot use the same client library to access random REST APIs. You use&#x2F;write one library to access Twitter&#x27;s REST and another to access Facebook&#x27;s REST. You could argue that you use HTTP in both cases, but that&#x27;s just the underlying transport protocol - not the API &quot;language&quot; itself. Because of that fact I blame REST for the millions of developers hours wasted in re-implementations of hundreds and thousands versions of the same &quot;concept&quot;.<p>The REST &quot;idea&quot; sure looks sexy when you put it next to an atrocity like SOAP, but that&#x27;s one of its very few merits.