  With the emergence of Information and Communication Technologies (ICT) and
wireless embedded sensing devices into modern vehicles, Intelligent Transport
System (ITS) becomes a reality and an indispensable component of smart cities.
The purpose of ITS is to improve road safety and traffic efficiency as well as
offering infotainments services. In fact, warning drivers in the right time
about dangerous situations on the road and providing them with prior
information about traffic will undoubtedly leads to enhance driver's safety and
reduce traffic congestion. Technically speaking, ITS is based on
self-organizing wireless networks, known as vehicular ad-hoc networks (VANETs).
Mobile vehicles in VANET might play the role of stationary sensors in
infrastructure-based networks. They can detect, gather and disseminate
real-time data about traffic, driving conditions and potential hazards on
roads. In this respect, we review in this study, recent developments on the
design of VANET protocols and applications. We first introduce the architecture
of VANETs then we review their unique characteristics and applications.
Thereafter, we discuss the main research challenges and open issues to be
considered for designing efficient and a cost-effective VANET protocols and
applications.
