Content items = articles

I think I'm starting to understand Joomla!. The articles you publish everyday are called content items. Here's a meaty definition:

"A content item is a discrete piece of content within the Joomla! hierarchy. A content item may be associated with a particular Section/Category combination or a Static Content Item. Usually content items are displayed in the main body of your page. Content item is the last in the Section/Category/Content Items hierarchy or it can be a separate Static Content Item."

1. Joomla! hierarchy = Section/Category/Content-Items hierarchy, for example: business/marketing/how to sell people things they don't need, the section is business and the category is marketing.

[Observation: Joomla!'s hierarchy is a tree, but forests like folk taxonomies in del.icio.us allow for different categorizations, different ways of looking at the same thing. The tree versus forest distinction has been around for a long time though. I used to deal with trees all the time as a COBOL-CICS General Ledger computer consultant in corporate America. For example, better designed General Ledgers for corporations have corporate reporting structures built into the hierarchy of accounts and these hierarchies are forests, not trees. The various reports of a company will break down the same information in different ways.]

2. Main body of page = center, so...

3. Components must display content items.

4. An ItemId must be the unique identifier of a content item, right?

[No, if you look at the menu manager screen under administrator, ItemId is in one column and CID which must mean content id is in another. Not the same.]