In wireless networks, information is vulnerable to a variety of active and passive attacks due to the broadcast nature and superposition feature of the wireless medium which makes it difficult to ensure secure communication in the presence of adversarial users. A traditional technique for ensuring security in wireless network transmission is cryptography, which transforms data into a format that is unreadable by unauthorized users. However, the modern wireless networks’ heterogeneity and vehicle maneuverability make it extremely difficult for traditional security procedures to authenticate and secure the system. Cryptography alone is insufficient to protect data from unauthorized users, given the rapid advancements in quantum computing and code-breaking tools. A potential solution for the security problems with traditional cryptography mentioned earlier is Wireless Physical Layer Security (WPLS). This chapter presents a detailed overview of the security limitations and challenges of conventional cryptography, concepts, various approaches, performance metrics, emerging trends, and applications of PLS techniques. Also, future research directions for PLS techniques have been presented.