In this chapter, we describe the three methods used to build the Edm model in Web API OData and walk you through every required aspect to build a simple Customer-Order Edm model. It’s recommended to use convention model builder to build Edm model for its simplicity and convenience. However, if user wants to make more control on the model building, or he doesn’t have the corresponding CLR classes, the non-convention model builder and the explicitly method are also very useful.