We describe Veins, an open-source model library for (and a toolbox around) OMNeT++, which supports researchers conducting simulations involving communicating road vehicles—either as the main focus of a study or as a component. Veins already includes a full stack of simulation models for investigating cars and infrastructure communicating via IEEE 802.11 based technologies in simulations of Vehicular Ad Hoc Networks (VANETs) and Intelligent Transportation Systems (ITS). Thanks to its modularity, though, it can equally well be used as the basis for modeling other mobile nodes (like bikes or pedestrians) and communication technologies (from mobile broadband to visible light). Serving as the basis for hundreds of publications and university courses since its beginnings in the year 2006, today Veins is both one of the most mature and established tools in this domain. In this chapter, we give a brief overview of recent developments regarding the architecture, simulation models, and supporting code of Veins; we also present two practical use cases, discuss two extensions, and conclude with a brief discussion of using Veins as a virtual appliance. The framework, code examples, and tutorial simulations can be downloaded from http://veins.car2x.org.