Over the past few decades, the intelligent transportation system (ITS) have emerged with new technologies and becomes the data-driven ITS, because the substantial amount of data is assembled from the multiple sources. Vehicular Ad hoc networks (VANETs), are a particular case of ad hoc networks that are used in the smart ITS. VANETs have become one of the most, encouraging, promising, and fastest-growing subsets of the mobile ad hoc networks (MANETs). They are comprised of smart vehicles and roadside units (RSUs) and on-board units (OBUs) which communicate through unreliable wireless media. Other than lacking infrastructure, delivering entities move with different increasing speeds. Thus, this delays establishing reliable end-to-end communication paths and having efficient data transfer. In this manner, VANETs have diverse system concerns and security difficulties in getting the accessibility of ubiquitous availability, secure communication, interchanges, and reputation management system. Which influence the trust in collaboration and arrangement between the portable system. By their fluctuation in nature, they are genuinely defenseless against assaults, which may result in life-jeopardizing circumstances. In this survey, we provide an extensive overview of the ITS and the evolution of ITS to VANETs. We provide the details of VANETs, discussed the privacy and security attacks in VANETs with their applications and challenges. We address the effectiveness of VANETs and cloud computing with architecture and related privacy and security issues. We also examined the communication protocols for each network layer with the relevant attacks occurred at each layer. We also discussed the potential benefits of the different proposed techniques related to VANETs, application, and challenges in details. In the end, we provide a conclusion with some open and emerging issues in VANETs.