As a result of the LOADS of requests from Flickr users, the Flickr Team has finally launched a long-awaited feature. It’s called “Collection” and it works like “Subsets”.
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.
This feature comes in handy for practically anybody who uses Flickr to share their photos. You can create a collection that consists of all your friends’ wedding photos, or another one to store your vacation photos, or another one to store your sunset or sunrise photos.
Now there’s more reason to hang out in Flickr, no? 
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Oh god finally, been waiting for this forever.
pelf: It just means that they do hear us!