The document summarizes the Flickr API by discussing why it was created (for people to share photos), what some of its key features are (uploading photos, tagging, commenting, geotagging, etc.), and how developers can access it through over 160 API methods and tools like the Geo API Explorer and Not so sekret garden developer documentation. It also provides some usage statistics and highlights the history and growth of Flickr and its API over time from its beginnings in 2003 to its current features and tools.