In this contribution, the main characteristics of MUMPS, the host language of AIDA, are briefly discussed. This is basically an introductory text for readers who had had no previous experience with MUMPS, on the programming side. After a short introduction, its history is summarized. Then the language itself is introduced and illustrated with examples; for the sake of brevity not all commands, functions and other features are discussed. In the next section, an introduction to MUMPS' stronghold is given: the database structure. Finally, we give the main reasons why we have chosen MUMPS as AIDA's host language. In the appendices, attention is given to the language standardization process, the visibility of MUMPS and its availability, sources of further information and the most important text books on MUMPS (in English).