This paper presented an overview and tutorial of various issues in VANET. Various types of research challenges are highlighted in context of vehicular communication. In particular, this paper presented a review of VANET architecture, transmission modelling, mathematical aspects of signal modelling, routing protocols and security. A comparative analysis of different routing algorithms in the field of VANET has been presented. It also highlighted the main issues in routing algorithms. The performance metrics for routing algorithms, discussed in this paper, were PDR with respect to average velocity of vehicles, node density and system throughput. The other parameters of interest discussed widely in the paper were average end-to-end delay and routing overheads. The paper concluded that some algorithm perform well in urban environment while others are suitable for highway environment. It was also concluded that proper modeling techniques are necessary for designing a seamless communication in VANET for a particular environment. Finally, main research challenges and areas of interest in vehicular communication were discussed.