From the Flickr Blog.
Today we launched what's probably the most requested feature over the last few years: a way to categorize and organize your photo sets! In the past this feature has been referred to as "sets of sets" or "subsets". After today, we'll know it as "collections".
What are collections, you ask? A collection is a container into which you can place either sets or other collections, allowing you to create a hierarchy as deep as 5 collections. You can place as many of your sets into a collection as you like, and a set can be in as many different collections as you like.
I've already thrown together nine collections. It was damn easy.
