Glossary of Drupal terminology

Block
A small box containing information or content placed in a region of a web page (e.g. in a sidebar, below or above the content, or in any other region the current theme allows).
Comment
Text attached to a post intended to clarify, explain, criticize, or express an opinion on the original post.
Node
The basic unit of content in Drupal, often referred to as a "post". All content that can be created using the "create content" menu is a node. Keep in mind that comments, blocks, and users are not nodes.
Published
A post that is viewable by every visitor of the site, regardless of whether he is logged in (see also "Unpublished").
Role
A classification users are placed into for the purpose of setting users' permissions. A user receives the combined permissions of all roles to which he or she is subscribed.
Taxonomy
A categorization system that allows the building of complex hierarchial or relational structures and tagging of content (see taxonomy help).
Unpublished
A post that is only viewable by administrators and moderators.
User
A person who has an account at your Drupal site, and is currently logged in with that account.
Visitor
A person who does not have an account at your Drupal site or a person who has an account at your Drupal site but is not currently logged in with that account. A visitor is also called an "anonymous user".