A fundamental building block of any Grid infrastructures is the Grid information service and the information model. The information model describes the entities and relationships between entities within the infrastructure along with their semantics. The realization into a concrete data model defines the syntax by which these concepts can be exchanged. This data model enables consumers of information to efficiently find the information they require and ensures that there is agreement on the meaning with the information producer. The need for a common information model is therefore critical for the seamless interoperation of Grid infrastructures. A number of example interoperation activities are presented which highlight this point and the requirement for a common schema in general. An attempt to achieve interoperability between multiple Grid infrastructures, which was demonstrated at Super Computing 2006, helped motivate work on a common schema within the Open Grid Forum. The result of this effort, GLUE 2.0, which in itself defines the current view of Grid computing, is presented.