The density of traffic is increasing on the daily basis in the world. As a result, congestion, accidents and pollution are also increasing. Vehicular Ad-hoc Network (VANET), a sub class of Mobile Ad-Hoc Network (MANET), is introduced as solutions to manage congestion and accidents on roads. VANET is gaining attention among researchers due to its wide-range applications in the field of Intelligent Transportation System (ITS). The paper focus on communication architectures along with its components and access technologies, challenges and security attacks in VANET. Furthermore, it deals with broad categorization various research domains, research methodologies and research models in VANET. At last, paper explores various application area of VANET.