The document discusses using the Lithium PHP framework to build a photo blog application. It provides examples of defining a Photos model to interact with photo data, building views to display and edit photos, implementing a PhotosController to handle requests and define actions, and setting routes. The model saves photo data and tags to the database. Views are used to display photo details, edit forms, and render tags as links. The controller handles index, view, add, edit and nearby location based actions. Routes are also defined, including one to directly serve photo image files.