Flickr is an online photo gallery where users can upload and share their photos with others. To use Flickr, users must create a Yahoo email account if they do not already have one. They can then sign in to their Yahoo account on Flickr to upload photos, add photos to their photostream for others to see, search for and add friends, and explore photos shared by other users. Flickr allows users to share photos, receive comments from others, and participate in forums and discussions about their photos.