This document reviews different techniques for congestion control in mobile ad hoc networks (MANETs). It begins with an introduction to MANETs and discusses how congestion can occur and degrade network performance. The literature survey section then summarizes several recent studies that have proposed various congestion control methods. These include adaptive data rate and control of hello packets, cross-layer approaches, hop-by-hop congestion control algorithms, avoiding congestion by monitoring bandwidth capacity, and fuzzy logic based congestion control. The document concludes that congestion is a major issue in MANETs and different control mechanisms aim to improve throughput, delivery ratio and reduce packet loss and delay.