The document discusses BOSS (Build Your Own Search Service), which is a search API provided by Yahoo. It allows developers to integrate search functionality into their applications by providing RESTful APIs, authentication via OAuth, and tools to customize search results. The document provides examples of how BOSS can be used to perform different types of searches across web, images and news and filter or re-rank results. It also highlights some open source projects that have been built using BOSS and lists additional resources for developers.