The Internet of Things (IoT) is transforming daily-use hardware—such as air conditioners, refrigerators, water heaters, water kettles, projectors, and fitness bands—into intelligent, inter-associated systems that generate massive volumes of real-time data. To efficiently manage this data, APIs are used to facilitate structured collection, filtering, storage, security, and analytics. The Cisco seven-layer IoT model provides a clear framework for this architecture, from physical hardware sensing to business intelligence integration. IoT data management involves several techniques, including temporal and spatial aggregation, secure access control, and scalable storage solutions. Communication protocols like MQTT and RESTful APIs play a key role in data transfer across layers. Technologies such as edge and fog computing support early-stage data processing, while cloud platforms handle long-term analytics and decision-making. Security remains a critical concern, with emphasis on confidentiality, access control, and license management. This chapter explores these dimensions, demonstrating the importance of efficient data handling to support real-time applications, smart grids, and industrial automation. IoT associates everyday hardware like air conditioners (AC), fridges, water heaters, ovens, projectors, vehicles, washing machines, fitness bands, wristwatches, and even shoes to the Internet. IoT systems generate a high volume of data, and cloud computing facilitates that data to reach its destination with the help of the IoT communication protocol. A large amount of data is always transmitted from IoT hardware to another IoT hardware (such as edge, fog, cloud, or database server) using the IoT communication protocol.