RTML has all the elements of a programming language including:

» Control flow
» Variables
» Iteration or loops
» Conditional execution
» Subroutine and function calls

Intention of RTML is to provide a conduit between content and presentation i.e. between the record of your store and the HTML pages that display your record. One of the advantage of RTML is if you don't have any idea about the database and also not aware of how to write HTML though , with the help of RTML you can develop your webpage.RTML makes it possible to define the structure of a whole site, not just the contents of individual pages.
 
You achieve complete control over the design of your store and also expand existing functionality of your store.RTML is not client side scripting even its not server side.One of the drawback is that it executed only once.you can not database manipulation.

Thus RTML is a real programming language, not just a page description language.  
RTML is a proprietary programming language Yahoo Merchant Solutions (Yahoo! Store) uses to build store templates. Templates are programs that create the web pages that make up any Yahoo! Merchant Solutions Store. While the "door is open" to anyone (through the Advanced Edit Interface in the Yahoo! Store Manager) to get to the templates and change them, there is very little information available online on how to do this and how RTML works. In addition, Yahoo! Merchant Solutions technical support does not cover RTML and custom templates. Up until now, anyone interested in venturing into the world of custom templates and RTML was left to his/her own devices to learn - usually through trial and error. With RTML 101, you can learn the ins and outs of RTML and Yahoo! Store Templates.