In the advent of the 6G era, the convergence of physical and digital domains mark an evolution towards “perceptual networking.” This innovative approach marks a transformative stride towards network awareness, where wireless systems not only transmit data but also perceive and interpret the surrounding physical environment. This convergence extends across diverse platforms, from vehicles and drones to urban surveillance and agricultural equipment. To enable this transition, the wireless industry advocates for networks endowed with sensing capabilities akin to radar systems, termed Integrated Sensing and Communications (ISAC). ISAC embodies a paradigm shift from conventional communication-centric networks to systems capable of perceiving and interpreting their environment. This chapter explores the coexistence, collaboration, and integrated design of wireless communication and radar sensing, showcasing ISAC as a pivotal technology in future wireless networks. Through synergistic co-design strategies and unified waveform approaches, ISAC promises optimized performance and enhanced system efficiency, positioning it as a revolutionary catalyst in the domain of wireless communications.