This document reviews different criteria for designing routing protocols in mobile ad hoc networks. It discusses several qualitative and quantitative characteristics that make for an effective routing protocol, including being loop-free, distributed, fast, and power efficient. The document then classifies routing protocols based on various criteria such as whether they use pre-computed or on-demand routing, periodic or event-driven updates, flat or hierarchical network structures, and whether they establish single or multiple paths. It reviews common routing protocol types like proactive, reactive, source routing, and hop-by-hop routing. In conclusion, the document emphasizes that routing protocols are needed to dynamically find optimal paths between sources and destinations across multiple hops in mobile ad hoc networks.