This document reviews protocols for mobile ad hoc networks (MANETs). It discusses how MANETs are self-configuring, decentralized wireless networks that allow nodes to communicate through wireless links. Routing in MANETs is challenging due to the frequent changes in network topology as nodes move. The document classifies MANET routing protocols as proactive, reactive, or hybrid and discusses examples of each type. It also reviews the evolution of MANET research from early packet radio networks to today's standards and ongoing work. Key challenges for MANET implementations include dynamic topologies, device discovery, and limited bandwidth and power.