A Mobile ad hoc network (MANET) is a self organized system which doesn’t have any pre-defined network infrastructure where mobile devices are connected by wireless links. Hence, a MANET can be constructed quickly at a low cost, as it doesn’t rely on existing network infrastructure. This paper presents a review on different techniques used to detect and mitigate the black hole attack in MANET i.e. for single black hole and also for cooperative black hole attack which are a serious threat to ad hoc network security. In cooperative black hole attack multiple nodes collude to hide the malicious activity of other nodes; hence such attacks are more difficult to detect. In this paper a comparison of various techniques that have been proposed in the literature for detection and mitigation of such attacks is presented.