General concepts

Last updated September 24, 2010. Created by esmerel on April 1, 2005.
Edited by silverwing, Dave Reid, jhodgdon, MGParisi. Log in to edit this page.

This page discusses some general concepts that will be useful as you begin to explore Drupal. The remaining topics in this section go into more detail on a few of these concepts.

Module

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.

User, Permission, Role

Every visitor to your site, whether they have an account and log in or visit the site anonymously, is considered a user to Drupal. Each user has a numeric user ID, and non-anonymous users also have a user name and an email address. Other information can also be associated with users by modules; for instance, if you use the core Profile module, you can define user profile fields to be associated with each user.

Anonymous users have a user ID of zero (0). The user with user ID one (1), which is the user account you create when you install Drupal, is special: that user has permission to do absolutely everything on the site.

Other users on your site can be assigned permissions via roles. To do this, you first need to create a role, which you might call "Content editor" or "Member". Next, you will assign permissions to that role, to tell Drupal what that role can and can't do on the site. Finally, you will grant certain users on your site your new role, which will mean that when those users are logged in, Drupal will let them do the actions you gave that role permission to do.

You can also assign permissions for the special built-in roles of "anonymous user" (a user who is not logged in) and "authenticated user" (a user who is logged in, with no special role assignments). Drupal permissions are quite flexible -- you are allowed to assign permission for any task to any role, depending on the needs of your site.

Node

A node in Drupal is the generic term for a piece of content on your web site. (Note that the choice of the word "node" is not meant in the mathematical sense as part of a network.) Some examples of nodes:

• Pages in books
• Discussion topics in forums
• Entries in blogs
• News article stories

Each node on your site has a Content Type. It also has a Node ID, a Title, a creation date, an author (a user on the site), a Body (which may be ignored/omitted for some content types), and some other properties. By using modules such as the contributed Content Construction Kit (CCK) module, the core Taxonomy module, and the contributed Location module, you can add fields and other properties to your nodes.

Comment

Comments are another type of content you can have on your site (if you have enabled the core Comment module). Each comment is a typically small piece of content that a user submits, attached to a particular node. For example, each piece of discussion attached to a particular forum topic node is a comment.

Taxonomy

Drupal has a system for classifying content, which is known as taxonomy and implemented in the core Taxonomy module. You can define your own vocabularies (groups of taxonomy terms), and add terms to each vocabulary. Vocabularies can be flat or hierarchical, can allow single or multiple selection, and can also be "free tagging" (meaning that when creating or editing content, you can add new terms on the fly). Each vocabulary can then be attached to one or more content types, and in this way, nodes on your site can be grouped into categories, tagged, or classified in any way you choose.

Database

Drupal stores information in a database; each type of information has its own database table. For instance, the basic information about the nodes of your site are stored in the Node table, and if you use the CCK module to add fields to your nodes, the field information is stored in separate tables. Comments and Users also have their own database tables, and roles, permissions, and other settings are also stored in database tables.

Path

When you visit a URL within your Drupal site, the part of the URL after your base site address is known as the path. When you visit a path in your Drupal site, Drupal figures out what information should be sent to your browser, via one or more database queries. Generally, Drupal allows each module you have enabled on your site to define paths that the module will be responsible for, and when you choose to visit a particular path, Drupal asks the module what should be displayed on the page.

For instance, this site (drupal.org) is (of course) built with Drupal. The page you are now viewing is http://drupal.org/node/19828, whose path is "node/19828". The module that is responsible for this path is the core Node module, so when you visit this page, Drupal lets the Node module determine what to display.

To determine the path to a particular page on your site, for purposes of creating a link, go to the page you want to link to and look at the URL in the address bar. By default the URL, after the base address of your site, will begin with '?q='. When 'Clean URLs' are enabled you will see a directory structure in the URL. The "path" for use in a menu item is the part of the URL after the site's base address and without the "?q=".

Theme

The theme controls how your site is displayed, including the graphic look, layout, and colors. A theme consists of one or more PHP files that define the HTML output of your site's pages, along with one or more CSS files that define the layout, fonts, colors, and other styles.

Region, Block, Menu

Pages on your Drupal site are laid out in regions, which can include the header, footer, sidebars, and main content section; your theme may define additional regions. Blocks are discrete chunks of information that are displayed in the regions of your site's pages. Blocks can take the form of menus (which are concerned with site navigation), the output from modules (e.g., hot forum topics), or dynamic and static chunks of information that you've created yourself (e.g., a list of upcoming events).

There are three standard menus in Drupal: Primary Links, Secondary Links, and Navigation. Primary and Secondary links are built by site administrators, and displayed automatically in the page header of many themes (if not, you can enable their blocks to display them). Navigation is the catch-all menu that contains your administration menus, as well as links supplied by modules on your site. You can also create your own custom menus, and display them by enabling their blocks.

You can customise menus in several ways, such as reordering menu items by setting their “weight” or simply dragging into place, renaming menu items, and changing the link title (the tooltip that appears when you mouse over a menu item). You can move a menu item into a different menu by editing the Parent property of the menu item.

You can also add custom menu items to a menu, from the Add menu item tab of the Menu administration screen. To create a menu item, you will need to provide the path to the content (see above).

In all cases a menu item will only be shown to a visitor if they have the rights to view the page it links to; e.g., the admin menu item is not shown to visitors who are not logged in.

See also

• Drupal Terminology
• The rest of the pages in this section of the Handbook