This chapter provides some information about i2b2 and the IDRT tools in general. IDRT Platform Architecture An overview how the different parts of the IDRT interact with each other and the i2b2 platform. How the i2b2 modifier ability is used by the IDRT for allowing secondary entities in a regular i2b2 installation. When working with large datasets - a scenario not unusual if your i2b2 instance matures - certain tricks will make loading data and calculating queries faster. The i2b2 ontology is primarily used for navigation, but often there is more than one way to represent your domain of knowledge. We will give a short introduction to the i2b2 database schema and provide some lessons learned for populating the ontology. | 
