Overview of common approaches to network based functional annotation. In each hypothetical example, the proteins with known function are annotated by a symbol that represents their function. Proteins with unknown function are labeled with question marks. As seen on the left, connectivity/modularity based schemes transfer function based on direct interactions. As seen in the middle, proximity based schemes diffuse function through the network. Finally, as seen on the right, pattern based schemes derive templates of functional interactions and interpolate these patterns accordingly to infer novel functions for proteins.