Abstract
The integration of blockchain and IoT presents tremendous potential for unlocking new opportunities and capabilities. With additive decentralized features, businesses and individuals can benefit from increased security, transparency, and efficiency in various applications. This chapter first presents the technical aspects of this integration, including the role of smart contracts in decentralized IoT systems and how blockchain enhances the security, stability, and transparency of IoT networks. Then, a step-by-step tutorial for developing smart contracts and ledger on Ethereum blockchain is presented, particularly from the perspective of IoT nodes. The considered scenario is for an IoT device that writes/retrieves data from the blockchain; however, the presented methodology can easily be extended for different use cases.