Flickr is an online photo album owned by Yahoo.
website and web services suite, and an online community platform, which is generally considered an early example of a Web 2.0 application. In addition to being a popular Web site for users to share personal photographs, the service is widely used by bloggers as a photo repository. Its popularity has been fueled by its innovative online community tools that allow photos to be tagged and browsed by folksonomic means.
Flickr allows users to categorize their photos into “sets”, or groups of photos that fall under the same heading. However, sets are more flexible than the traditional folder-based method of organizing files, as one photo can belong to one set, many sets, or none at all.
Picasa is a computer application for organizing and editing digital photos owned by Google, it is similar to Flickr, it also offers several basic photo editing functions, including color enhancement, red eye reduction and cropping.