Security has become a primary concept in order to provide protected communication between mobile nodes in a hostile environment. Recently there has been much research activity in the emerging area of intermittently connected ad hoc networks and delay tolerant networks. There are different types of delay tolerant n/ws, depending on the nature of the network environment. Routing in delay tolerant n/ws is one of the key components in the Delay Tolerant N/w architecture. Trust is an important aspect of mobile ad hoc n/w. It enables entities to cope with uncertainties and uncontrollability caused by the free will of others. Trust computation and management are highly challenges issues in Mobile Ad hoc N/ws. This report also discusses different no of scenarios of Mobile Ad hoc n/w which we implement in our simulation. The role of infrastructure-less mobile ad hoc n/ws in ubiquitous n/ws is outlined. In a Mobile Ad hoc N/w there are no dedicated routers and all network node must contribute to routing. Classification of routing protocols for Mobile Ad hoc N/w is based on how routing information is acquired and maintained by mobile nodes and on roles of n/w nodes in a routing. Now a days Mobile Ad hoc N/w are most technique in computing mobile. This paper focused on the evolution of the Mobile Ad hoc n/w, the challenge in it and a wide area of it’s applications. the first section provide a brief info about the history and evolution of Mobile Ad hoc N/w, next to it discuss the major challenges in Mobile Ad hoc N/w and towards the end mentioned some of the application of Mobile Ad hoc N/w.