Due to the infrastructure-less and no central administration architecture, Mobile Adhoc Networks (MANETs) gained significant interest in various wireless information transfer related applications. However, the selection of an optimal path to transmit the data is a more critical issue in MANETs because the nodes are resource-constrained and also have mobility. To provide an optimal solution to this constraint, various methods are proposed in earlier. Initially, some basic routing protocols are developed and further by modifying the base protocols so many strategies are developed. The proposed Research paper outlines a detailed survey about the earlier developed such strategies and also done a fined classification based on the methodology they followed. Broadly the comprehensive routing approaches are classified into two classes, namely single metric-based approaches and multiple metricsbased approaches. The further classification is done based on the routing protocol used at the base. Due to the widespread utilization of meta-heuristic algorithms, some authors used those techniques also in the discovery of an optimal path and some approaches are outlined in this paper. Moreover, at every phase, a fine and detailed comparison is shown through various constraints.