Photorank is a platform that assesses users' photo-sharing activities across various networks, such as Facebook, Twitter, Flickr, Instagram, and Picplz. It calculates a score based on reach, quality, and activity, with a focus on the last 21 days. The score reflects the user's ability to influence a wide audience through their photos. Factors such as interactions, likes, comments, and retweets contribute to the score. Photorank aims to help individuals understand their social photography skills and discover talented photographers to follow.