'''''RESTful''''' (REpresentational State Transfer) '''''API''''' (Application Programming Interface) '''''DLs''''' (Description Languages) are [[formal language]]s designed to provide a structured description of ana [[REST]]ful [[web API]] that is useful both to a human and for automated machine processing. API Description Languages are sometimes called [[interface description language]]s (IDLs). The structured description might be used to generate a documentation for human [[programmer]]s; such documentation is easier to read than a free-form document, since everyall documentation generated by the same tool follows the same formatting conventions. Additionally, the description language is usually precise enough to allow automated generation of various software artifacts, like libraries, to access the API from various programming languages, which takes the burden of manually creating them off the programmers.
==History==
There are two previous major description languages,: [[Web Services Description Language|WSDL2.0]] (Web Services Description Language) and [[Web Application Description Language|WADL]] (Web Application Description Language). Neither is widely adopted in the industry for describing RESTful APIs, citing poor human readability of both and WADL being actually unable to fully describe a RESTful API.<ref name="slideshare.net">http://www.slideshare.net/SOA_Software/api-description-languages</ref>
