Collection
A Collection is a list which has child entities related to it together with metadata to describe itself. Collections are often used to group Assets and other Collections together as a way to organize them similar to creating a directory on a computer hard drive. Unlike a directory, members of a collection can be members of multiple collections at once.
Collection content is unordered by default, and returned via the search engine in an ordered determined by the search query, however if you have chosen to order the collection this ordering can also be used when returning the results.
Collection metadata
There is metadata on the collection such as it's title and it's creator. Additional metadata fields can be applied to collections by using metadata views.
Ownership and ACLs
The User that creates a collection is consider it's owner. Additional rights to be able to view, edit or delete a collection can be edited using ACLs.
Additionally a collection can have an ACL applied to it that any member of the collection will inherit.