1. What is Drupal ?
Drupal is an open-source platform and content management system for building dynamic web sites offering a broad range of features and services including user administration, publishing workflow, discussion capabilities, news aggregation, metadata functionalities using controlled vocabularies and XML publishing for content sharing purposes. Equipped with a powerful blend of features and configurability, Drupal can support a diverse range of web projects ranging from personal weblogs to large community-driven sites.

2. What is a CMS ?
A content management system (CMS) is a collection of procedures used to manage work flow in a collaborative environment. These procedures can be manual or computer-based. The procedures are designed to:
— Allow for a large number of people to contribute to and share stored data
— Control access to data, based on user roles. User roles define what information each user can view or edit
— Aid in easy storage and retrieval of data
— Reduce repetitive duplicate input
— Improve the ease of report writing
— Improve communication between users
In a CMS, data can be defined as almost anything – documents, movies, pictures, phone numbers, scientific data, etc. CMSs are frequently used for storing, controlling, revising, semantically enriching, and publishing documentation. Content that is controlled is industry-specific. For example, entertainment content differs from the design documents for a fighter jet. There are various terms for systems (related processes) that do this. Examples are web content management, digital asset management, digital records management and electronic content management. Synchronization of intermediate steps, and collation into a final product are common goals of each.

3. What is a web content Management system ?
A Web content management system (WCM, WCMS or Web CMS) is content management system (CMS) software, implemented as a Web application, for creating and managing HTML content. It is used to manage and control a large, dynamic collection of Web material (HTML documents and their associated images). A WCMS facilitates content creation, content control, editing, and essential Web maintenance functions.
The software provides authoring (and other) tools designed to allow users with little knowledge of programming languages or markup languages to create and manage content with relative ease.
Most systems use a database to store content, metadata, or artifacts that might be needed by the system. Content is frequently, but not universally, stored as XML, to facilitate reuse and enable flexible presentation options.
A presentation layer displays the content to Web-site visitors based on a set of templates. The templates are sometimes XSLT files.
Most systems use server side caching boosting performance. This works best when the WCMS is not changed often but visits happen on a regular basis.
Administration is typically done through browser-based interfaces, but some systems require the use of a fat client.
Unlike Web-site builders, a WCMS allows non-technical users to make changes to a website with little training. A WCMS typically requires an experienced coder to set up and add features, but is primarily a Web-site maintenance tool for non-technical administrators.

4. Which are commonly used PHP based CMSs ?
— Drupal
— Joomla
— WordPress
— TYPO3

5. Why are so many Drupal versions available – 4.x, 5.x …7.x? Which one should I use?
It is recommended that you run the most current stable release. This can always be found at the Drupal Project page. However, if there are no compelling features in the latest version, a contrib module that is important to you isn’t ready or you don’t have time, there is no need to rush your upgrade as long as security updates are available for the version you are running. Latest version as of now is 8.x.

6. What is a Module in drupal ?
A module is software (code) that extends Drupal features and/or functionality. Core modules are those included with the main download of Drupal, and you can turn on their functionality without installing additional software. Contributed modules are downloaded from the Modules download section of drupal.org, and installed within your Drupal installation. You can also create your own modules; this requires a thorough understanding of Drupal, PHP programming, and Drupal’s module API.

7. What are hooks in Drupal ?
Allow modules to interact with the Drupal core.
Drupal’s module system is based on the concept of “hooks”. A hook is a PHP function that is named foo_bar(), where “foo” is the name of the module (whose filename is thus foo.module) and “bar” is the name of the hook. Each hook has a defined set of parameters and a specified result type.
To extend Drupal, a module need simply implement a hook. When Drupal wishes to allow intervention from modules, it determines which modules implement a hook and calls that hook in all enabled modules that implement it.

The string “hook” is used as a placeholder for the module name in the hook definitions. For example, if the module file is called example.module, then hook_help() as implemented by that module would be defined as example_help().