This review discusses the application of statistical physics to the study of vehicular traffic and related systems. It highlights the use of both analytical and numerical techniques to understand complex phenomena such as phase transitions, criticality, self-organized criticality, metastability, and hysteresis in traffic systems. The paper emphasizes the importance of microscopic models, particularly "particle-hopping" models formulated using cellular automata (CA), in capturing the dynamics of traffic. It also reviews various theoretical approaches, including fluid-dynamical theories, kinetic theories, and car-following theories, and discusses their implications for understanding traffic behavior. The review covers empirical observations, such as acceleration noise, formation of traffic jams, flux-density relations, and time- and distance-headways, and compares these with theoretical models. It also explores the effects of quenched disorder on traffic and discusses the similarities between traffic systems and other complex systems. The paper concludes with a summary of the current state of research and future directions in the study of traffic and related systems.This review discusses the application of statistical physics to the study of vehicular traffic and related systems. It highlights the use of both analytical and numerical techniques to understand complex phenomena such as phase transitions, criticality, self-organized criticality, metastability, and hysteresis in traffic systems. The paper emphasizes the importance of microscopic models, particularly "particle-hopping" models formulated using cellular automata (CA), in capturing the dynamics of traffic. It also reviews various theoretical approaches, including fluid-dynamical theories, kinetic theories, and car-following theories, and discusses their implications for understanding traffic behavior. The review covers empirical observations, such as acceleration noise, formation of traffic jams, flux-density relations, and time- and distance-headways, and compares these with theoretical models. It also explores the effects of quenched disorder on traffic and discusses the similarities between traffic systems and other complex systems. The paper concludes with a summary of the current state of research and future directions in the study of traffic and related systems.