"BIM (Building Information Modelling) is a digital representation of physical and functional characteristics of a facility. A building information model is a shared knowledge resource for information about a facility, forming a reliable basis for decisions during its life-cycle; defined as existing from earliest conception to demolition." - BuildingSmart
 

Benefits

BIM delivers benefits within each of the design, construct and operate sections of the project life cycle. These benefits are enhanced when the process is considered as a whole and the information/data requirements are coordinated. They can be summarised as:

- Co-ordination

- Communication

- Data Management

- Analysis and Simulation

- Improved Productivity During Construction

- Better Information For Facilities Management

The different levels

Level of Development (LOD) is a scale that can be used to show the reliability of content that is expected to be included for specificmodel elements at different  times during model development. 

 Organisation

For the majority of projects, each designer or sub-trade will produce their own model. These models can be then combined or “federated” to create a single shared model. Interdisciplinary coordination is confirmed in the federated model. Required changes are made in the individual discipline models.

On large projects discipline models may be split into multiple, smaller models to make file sizes more manageable.