With the sale of Flickr to SmugMug, many users certainly expected some big changes, particularly as the service's 1TB of free storage was just too good to be true to begin with.
What Is Creative Commons?
Creative Commons is a non-profit that helps artists, like photographers, share their work for free using various standardized licenses that might require attribution or linking, or limit derivative uses. Basically, it provides standard legal forms that protect artists from having their work stolen or used without permission.
Notably, Flickr has been a partner to Creative Commons for many years now, and houses millions of photos that are licensed for free use via Creative Commons. However, those millions of photos were posted by users, and if those users do not upgrade, it is unknown just how many free-to-use photos will be lost. Fortunately, the issue has been brought to the attention of both Flickr and Creative Commons and a solution may be in the works.
Free Stock Photography
If you need stock photography to use for email newsletters, your website, or any other digital asset you are preparing, Flickr has been, and will likely continue to be, an excellent repository. Thanks to the use of the Creative Commons licenses, it is very clear what images you can use for commercial purposes, and what the terms of the use entail.