Introduction to Omeka 2.0 from Omeka on Vimeo.
An “item” is the basic unit of an Omeka site. An item may be a photograph with a single attached image file, a three-page letter with three attached image files (one for each page), or a record with no attached files (such as a “person” record).
Omeka sites by default have a space on the home page for recently added items and for “featured” items that are particularly interesting. You can mark items as “featured” when you add them (or later).
Tags allow you to link items together with terms of your choosing. When any two items have the same tag, the tag automatically turns into a link. Omeka sites allow you to browse items by tag.
Items within Omeka can be grouped into collections. Each item may belong to only one collection.
Collections are ways of organizing items, rather like file folders on your computer, or like collections in archives such as “Peter Strawhan files 05: Dunstan Collection” in the Special Collections of Flinders University. Collections provide a way to organize your items into separate, logically coherent groups. Items do not have to be in collections, but once an item is in a collection, it can’t be in any other collection. You can make as many links as you like between items in different collections, though, with tags and exhibits.