Abstract: Mobile Ad Hoc Network (MANET) is an independent, decentralized, highly mobile, self-maintaining, self-repairing, self-configurable wireless network, free to go from one place to another place. These networks do not have any pre-existing infrastructure. Every gadget has freedom to go randomly from one place to another and changes its links to other gadgets usually. Frequent mobility of nodes in MANETs make the establishment of these networks very difficult and challenging in real environment and its design is totally based on routing protocols. Routing protocols are the key factors of MANETs. Such networks have random, rapidly changing, dynamic multi hope topologies which are made up of limited battery power and limited bandwidth with variable capacity links. Their unique property makes it different from traditional networks such as easiness to communicate, mobility, etc. The introduction of MANET in smart environment needs new protocols for connecting devices to the internet. Routing protocols in smart environment must guarantee fairness, quality of service, connectivity among the nodes, both in ad-hoc networks and access points. The quality of service is decided by speed of data delivery and the service quality. Service quality depends upon the routing protocols used for data transmission. Interaction between MANET and IoT (Internet of Things) creates a new MANET-IoT system. These systems provide better mobility for users and reduce implementing costs of the network. Requirements of these networks are increasing in meeting rooms, emergency room, personal area networks, rescue operations, military operations. This study provides an overview of MANETs, relation between MANETs and IoT and its routing protocols by highlighting their functionality, benefits, characteristics, limitations. It also presents comparative analysis of their performance.