Node types

Drupal stores all of its content in nodes. Drupal's basic set of node types is relatively short, but quite flexible.

As of Drupal 5.x node types are now called 'Content types'

Blog Entry

Blogs, or weblogs, are another term for an online journal or diary. They are a place where members of the community can write their own thoughts and not have to worry about being on topic for the site.

Book Page

Book pages are designed to be part of a collaborative book. An example of a collaborative book is the Drupal developer documentation. Originally only book pages could be a part of a book but these days all node types can be part of a book.

Comment

Comments actually aren't nodes, they are their own special content type. Comments are what allow people to add comments to any other node that has been created.

Forum

Forums are sets of nodes and their comments. These are grouped together as belonging in one forum by assigning them the forum name, which is a taxonomy term. These forum names can be grouped in forum containers, which are other terms, of which they are children in a hierarchical vocabulary which is called "forums", and configured as only applicable to nodes of the "forum" type.

Page

Pages are simple nodes, typically used for static content that can (but are not required to) be linked into the main navigation bar

Poll

A poll is where a multiple choice question is asked and users can answer and see other people's answers to questions.

Story

Story pages are the generic page type that most content management systems have. Stories are generally used for information which is only relevant for a period of time (eg. news stories) and is expected to expire off of the page.

Additional types of nodes are provided by contributed modules.

Note: A common question is "What is the difference between page and story?" The answer is not much. There was more difference originally but they are merely different node types now and how you use them is up to you.