RHTML is an extension given to files generated based on the eRuby template system. RHTML are files that allow to embed code written in the interpreted Ruby language with the use of eRuba in an HTML document. The code contained in RHTML files is processed on the side of the web server with Ruby on Rails support. On its basis, an appropriate file is generated and sent to the client's web browser.

Ruby is an interpreted scripting language with simple syntax.