Collections are a basic unit of aggregation in Omeka. Unsurprisingly, they collect Items, ideally into logically consistent categories that add context to the Items. It’s worth noting that an Item can only belong to one Collection, no more.
Let’s make a new Collection, starting from the Admin dashboard that you see when you log in to Omeka.
Collections are described with the same Dublin Core metadata that Items in Omeka are, which is how they are usually contextualized.
Now, this Collection doesn’t have any Items, so it’s not doing us much good. Let’s add one to the collection.
Just keep doing that, and soon you’ll have a sizable Collection of Items. You can add as many Items as you like to a Collection, but each Item can only belong to one Collection.