All of three are CMS (Content Management System). All are very popular used by web designer to create websites very easily and attractive in very short time. In joomla easy to add content, template and design its as customer requirements. Joomla component and modules designed to help make the sites attractive and effectively through the plugin to add more convenience. SEO Friendly. Drupal CMS is huge all.
For me, I gave more detail here about the CMS. i am going to explain...
1. Plug - This is the best feature of Joomla. Joomla extensions backgrounds who are helping in the expansion.

2. Component: These are another effective feature that really has developed this website in a user amicable way. Web designers use these features, the expansion of the user, can get back to the site, and the translation of various materials to create search engine friendly URLs.

3. Modules: another popular functionalities, which are called on demand. Such as the calendar or the insertion of custom is likely to give a lot of flexibility can be demonstrated.

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