Like the previous edition, HIV Manual 4th edition has involved authors from The Chinese University of Hong Kong, The University of Hong Kong, Department of Health's Integrated Treatment Centre and three HIV services of the Hospital Authority – Queen Elizabeth Hospital, Princess Margaret Hospital, and Prince of Wales Hospital. Other contributors came from Department of Health's Centre for Health Protection – Social Hygiene Service, Tuberculosis and Chest Service – and Methadone Clinics Following a massive growth in size of the Manual 2007, the current Manual has chosen to be smaller, and hopefully, more user-friendly, by its appearance in three formats: web version, Apps (Android and iPhone), and the conventional hard copy. The chapters are grouped under 6 sections – basics of HIV medicine, public health management, clinical management, opportunistic and concurrent infections, neoplasia, special settings & the community. Algorithms continue to be a key component in most chapters. The references are limited to essential ones, and linkage to their sources can be effectively made if readers use the web or Apps for accessing the contents. All updated local guidelines on HIV management as well as the HIV/AIDS Report Form can be found in the Appendix.