Definitions and general guidelines are available on Creative Commons website. We also provide guidelines for attributing Creative Commons content. However, specifics about how to attribute All Rights Reserved content aren't provided. When in doubt, contact the photographer.
Did you know? When a photo on Flickr is pinned to or repinned on Pinterest and other sites, it will be clearly attributed with the name of the photographer, the title, and a link to the photo page. Flickr images embedded on other websites using one of the static Flickr farm URLs will also be clearly attributed when pinned or repinned.
See our forum thread about what's considered adequate attribution.