Drupal is a free and open source content management system that is written in PHP and is distributed under the GNU General Public License. It is one of the finest of CMS that has been developed so far. It is estimated that nearly 2.1% of all websites use Drupal as their back-end framework. Drupal core is the standard release of the CMS and contains the basic features of a content management system such as the account registration and maintenance, RSS feeds, menu management, page layout customization, taxonomy and system administration.
Till recently there are more than 30,000 free community-contributed extensions that are better known as contributed modules that can be used to alter and extend Drupal's core capabilities as well as add new features and customize its behaviour and appearance. The plug-in extensibility and the modular design of the Drupal makes it one of the most well known content management systems. It is also described as a web application framework as it satisfies all the feature requirements for such frameworks.
Drupal can run on any of the computing platform that supports both a web server that is capable of running PHP and a database that can store content and settings. The Drupal core has core modules, core themes, can be localized, auto-update notification, database abstraction, embraces windows developers and is easily accessible. The core can be extended through the third party developed modules that do not in any way change the core. If you are looking for PHP application development in India then it is better that you go for the developer that is well familiar with Drupal and knows how to work with it.