In recent years,traffic congestion and accidentsare seriously affecting people's daily life and the development of economy.As one important application of Internet of Things(IOT)in the road,VANETs contain great potential in improving the efficiency of road traffic and road safety.So it quickly draws widespread attention of governments,enterprises and academic institutions.In this paper,we discuss the opportunities,challenges and achievements of VANETs from aspects of the concepts,development,key technologies and standards.We first briefly introduce the concept and international research status of VANETs.Next we further study on some key technologies of VANETs,i.e.MAC,routing,broadcast,access of RSU,and security protocols.In the end,the progress of VANETs' standardization is introduced in detail. <<