license propel 
___MASK61___ , freedom - respecting software , or software libre is computer software distributed under terms that allow the software users to run the software for any purpose as well as to study , change , and distribute the software and any adapted versions . ___MASK61___ is a matter of liberty , not price : users , individually or collectively , are free to do what they want with it , including the freedom to redistribute the software free of charge , or to sell it , or charge for related services such as support or warranty for profit . Propel is a free , open - source ( MIT ) object - relational mapping toolkit written in PHP . It is also an integral part of the PHP framework Symfony and was the default ORM up to , and including version 1 . 2 . Web development is a broad term for the work involved in developing a web site for the Internet ( World Wide Web ) or an intranet ( a private network ). Web development can range from developing the simplest static single page of plain text to the most complex web - based internet applications , electronic businesses , and social network services . A more comprehensive list of tasks to which web development commonly refers , may include web engineering , web design , web content development , client liaison , client - side / server - side scripting , web server and network security configuration , and e - commerce development . Among web professionals , " web development " usually refers to the main non - design aspects of building web sites : writing markup and coding . Most recently Web development has come to mean the creation of content management systems or CMS . These CMS can be made from scratch , proprietary or ___MASK64___ . In broad terms the CMS acts as middleware between the database and the user through the browser . A principle benefit of a CMS is that it allows non - technical people to make changes to their web site without having technical knowledge . Symfony is a PHP web application framework and a set of reusable PHP components / libraries . Symfony was published as ___MASK61___ on October 18 , 2005 and released under the ___MASK2___ . The ___MASK2___ is a permissive ___MASK61___ license originating at the Massachusetts Institute of Technology ( MIT ). As a permissive license , it puts only very limited restriction on reuse and has , therefore , an excellent license compatibility . The ___MASK2___ permits reuse within ___MASK59___ provided that all copies of the licensed software include a copy of the ___MASK2___ terms and the ___MASK65___ notice . The ___MASK2___ is also compatible with many copyleft licenses , such as the ___MASK76___ ( GPL ); MIT licensed software can be integrated into GPL software , but not the other way around . PHP is a server - side scripting language designed primarily for web development but also used as a general - purpose programming language . Originally created by Rasmus Lerdorf in 1994 , the PHP reference implementation is now produced by The PHP Development Team . PHP originally stood for " Personal Home Page ", but it now stands for the recursive acronym " PHP : Hypertext Preprocessor ".