Building Information Modeling

BIM;- The terms is an acronym for Building Information Modeling. The terms has been very clearly described on wikipedia
To summarize - BIM is the model that details all the attributes of 3-D space as occupied by the building including the information about electrical fittings, plumbing, Air conditioning and HVAC, etc which can be used in the entire life-cycle of the building ( from planning to decommissioning/demolition).