Ad hoc network is a collection of nodes that is connected through a wireless medium forming dynamically changing topologies. A considerable effort
has been put into studying ad hoc networks over the past decade. Many routing protocols at different layers have been proposed and studied. In this paper, we
discuss about some of the most popular protocols that follow the table-driven and the source-initiated on-demand approaches and a few others, their challenges and
also discuss the future scope of ad hoc networks