1. Data (Node, ETC)
2. Modules
3. Blocks and Menus
4. User Permissions
5. Template

Data
Base of the system is collection of Nodes. – the data pool

Modules
These are functional plugins that are either part of the Drupal core (they ship with Drupal) or they are contributed items that have been created by members of the Drupal community.

Blocks and Menus
This is the next layer where we find blocks and menus. Blocks often provide the output from a module or can be created to display whatever you want, and then can be placed in various spots in your template (theme) layout. Blocks can be configured to output in various ways, as well as only showing on certain defined pages, or only for certain defined users.

User Permissions
Here is the next layer where settings are configured to determine what different kinds of users are allow to work and see.

Template
This is mainly the site theme or the skin. This is made up predominantly of XHTML and CSS, with some PHP variables intermixed

Understanding this flow of information is very important if you are facing A Drupal project targeted interview as the interviewer might test your overall knowledge  of  Drupal CMS by asking this sort of questions.

We can define any number of vocabularies (category types) and terms (categories)
e.g.
Controversial Content: (vocabulary)
– violence (term)
– adult content (term)

Genre (Vocabulary)
– Comedy (term)
– Romance (term)

We can config which content types are compatible with which vocabulary and which nodes are belong to which terms.

Some important drupal modules: Views, CCK, Path auto, FCK Editor, User points, Flags, Panels, Image cache

Views can be used to generate lists of content in various formats same as report generator works.

We can create roles (moderators, proof readers, content admins etc) and we can permit each task to each role. A user can have 1 or many roles.

Drupal themes are basically used to change the look and feel of the site.

Block is a section in a page (recent posts, news, vote to something, login box, navigation), which is movable to regions (header, footer, content top etc) in a page. Blocks can be configured to show/hide only to certain type of user roles, url patterns or some other advanced criteria. (Content area is not a block)

We can install CCK (Content construction kit) module and create content types. We can define the structure of each content type too.

A node is a unit of content. It has a type. Page, News or as Testimonial.

New module is developed by implementing hooks.  Hooks are defined in the API. At certain events, drupal hooks into our modules.

E.g. When a page is request processing start by initializing  -> hook_init
If the module name is mymodulename we can implement hook like this.

function mymodulename_init(){
}

It is the the settings.php file. The script will automatically populates database tables and configures the correct settings in the settings.php file.
It also explains how to do a “multi site” installation.

Frameworks – Zend Framework, cakephp

CMS’s – Drupal, joomla, wordpress

(wordpress is acutally a blog / CMS).