This document provides an introduction and overview of mobile ad hoc networks (MANETs). It discusses how MANETs are self-configuring networks formed by mobile nodes without a fixed infrastructure. The key characteristics of MANETs include using wireless communication, nodes acting as both hosts and routers, limited bandwidth and variable capacity links, energy-constrained operation, and dynamic network topology. The document also outlines some common applications of MANETs and provides an overview of different routing protocols used in MANETs, including proactive, reactive, and hybrid protocols. It gives a brief description of distance-vector and link-state routing approaches.