Collections are lists of entities that users can create, title and edit as they see fit. Each collection can be private or public. There is no limit to the number of collections that a single user can have, nor to the number of entities on each collection.
You can find a list of your collections under My Collections, in the My Data menu. From here you can access your collections and edit them, remove them and create new ones. Collections can also be created via individual release pages; see below.
Adding entities to a collection
Releases can be added to a collection either from the website or by using a music collection tool which tells the server which releases you have in a specified directory on your computer. This requires the releases to be tagged.
More generally, you can add an entity from the website by going to its page, and click the “Add to (collection name)” link in the sidebar. If the entity is already in one of the collections, for that particular collection you will be shown the option to remove it from it instead. If you currently have no collections, you will be asked to create one: there is also a link to create new a collection in the sidebar.
You can share your collections with others. This is mainly intended for community projects, but it can also be a good way to, say, have a shared “Music we have at home” collection with your family, or collect artists with funny names with your friends. To add collaborators to your collections, edit the collection and enter the editors you’d want as collaborators in the appropriate section (suggestion: ask first whether they’re interested, then add them!). Once they’ve been added as collaborators, they'll be able to add and remove entities from the collection in the same way as you, but they won't be able to change the title / description: that's still only for the collection owner to change.