Nice article from USA Today:
Flickr was created in 2003 by Stewart Butterfield and Caterina Fake, initially as a video game site. It was purchased by Yahoo in 2005, when it had 400,000 registered members.
Today, Flickr has 26 million members. Free accounts are limited to uploads of 100 megabytes monthly, or about 50 photos. “Pro” members get unlimited uploads. Yahoo won’t say how many paid members Flickr has.
Hitwise says the site’s market share among online photo sites leaped to 11.7% in March, from 4.5% the year before, after Yahoo added Flickr images to its search index.
“Yahoo has also made it really easy to post Flickr images on blogs, and that brings Flickr a lot of traffic,” analyst Dougherty says.
Flickr fans such as Petal in Alaska check out Flickr often, just to see what folks are saying about their work.
“I don’t know of another photo site where you can start a conversation based on just one photo,” she says. “It really gives people a lift to their day when someone has noticed one of their photos.”