The Internet of Things (IoT) for smart cities is a prominent research area aimed at enhancing urban living through intelligent, connected infrastructure and services. Research papers in this domain focus on integrating IoT sensors, actuators, and communication networks to enable smart traffic management, waste management, energy-efficient buildings, environmental monitoring, public safety, and citizen services. Key contributions include real-time data analytics, edge/fog-assisted processing, AI-driven decision-making, interoperability frameworks, and secure data sharing mechanisms. Recent studies also address challenges such as scalability, heterogeneity of devices, privacy, cybersecurity, and quality of service (QoS) to ensure reliable and resilient urban IoT ecosystems. By leveraging 5G/6G connectivity, blockchain, and predictive analytics, IoT-smart city research continues to drive the development of sustainable, efficient, and citizen-centric urban environments.