This chapter explores the evolution, functionality, and significance of Global Navigation Satellite Systems (GNSS) as a foundational pillar of modern technology. Moving beyond the foundational GPS, GNSS integrates multiple satellite constellations such as GLONASS, Galileo, and BeiDou, offering enhanced accuracy, redundancy, and global interoperability. It explores the components of GNSS, including satellite constellations, ground control systems, and user devices, highlighting their coordinated roles in delivering reliable positioning, navigation, and timing (PNT) services. The chapter analyses the advantages of GNSS over standalone GPS, focusing on improved signal resilience, precision, and multi-platform compatibility. It discusses GNSS applications across diverse sectors such as transportation, disaster management, agriculture, and environmental monitoring, emphasizing its contribution to technological innovation and societal advancement. Future developments in GNSS are also addressed, including the expansion of satellite constellations, integration with emerging technologies such as AI, IoT, and 5G, and advancements aimed at enhancing signal reliability and sustainability. The chapter concludes by underscoring GNSS’s vital role in fostering global connectivity, supporting sustainable development, and addressing global challenges such as urbanization and climate change. It emphasizes the importance of continuous innovation and international collaboration to fully realize GNSS’s potential in shaping a more connected, resilient, and efficient future. This chapter provides a comprehensive understanding of GNSS’s transformative impact, offering insights into its historical evolution, current applications, and future prospects.