This document provides an overview of Vehicular Ad-Hoc Networks (VANETs). It discusses the key components of VANETs including on-board units, roadside units, and a trusted authority. It describes the different types of communication in VANETs and lists some of the main applications like safety and convenience applications. The document also outlines some of the security requirements for VANETs, challenges in deploying them at scale, and techniques for establishing trust between vehicles.