This document is a comprehensive overview of the work on FAIR Digital Objects. It addresses a variety of aspects that have been discussed in the FDO Forum during the last two years and that are the subject of formal FDO Forum documents. Many of these documents have been written including examples and illustrations and in a verbose style allowing many to follow the discussion. This document will present an overview and should be seen as complementary to the FDO Requirements Specification document which has been extended as a result of the specification work.