VANETs have developed as one of the largest potential topics in the field of automotive industries with promising and challenging futures in various aspects. VANETs permit intelligent vehicles to generate their own organized network without the need of the stable network. In this paper we introduce VANETs and its comparison with MANETs, standard wireless access in VANETs like WAVE model partly based on OSI model. We present a comprehensive study on routing protocol in VANETs like position-based routing, Geo-Cast based routing, etc. and scheduling in VANETs like deadline-based scheduling, hybrid-based scheduling, etc. This paper presents open research issues in VANETs highlighting challenges like security and privacy issues, network congestion control issues, etc, numerous routing and scheduling issues in VANETs.