Vehicular Adhoc Network termed as VANET is a special type of Mobile Adhoc Network (MANET), where vehicles are the mobile nodes, which move with highly predictable mobility patterns. VANET solutions should be based on building new infrastructure and to implement new applications on transportation vehicles. Vehicle Traffic Safety Applications (TSA) can be the first step for safer roads. By increasing road safety, we can reduce and prevent the number of road accidents. The five layered architecture of VANET is formed from optimizing the seven layer Open Systems Interconnection (OSI) model and its functionalities are dealt in this work. High mobility and dynamic topologies always lead to intermittent the Quality of Service (QoS), higher delay and packet dropping issues in the network. It is prime importance to ensure VANETs security as their deployment in the future must not compromise the safety and privacy of their users. The vehicles in VANET always need to be connected with the target network. Many decision making schemes are surveyed and presented in this work. This survey also deals with the study of QoS in VANET's layered architecture and its related security threats in each layer of protocol stack. © 2006-2019 Asian Research Publishing Network (ARPN).