The Internet of Things (IoT) is an emerging technology that has revolutionized many areas of our daily lives, from smart homes to industrial systems, healthcare applications, transportation, and more, by enabling various entities (devices, objects, people, etc.) to connect and exchange data with each other using their unique identifiers to provide specific services. The security of the IoT environments therefore relies on managing the identities of interconnected entities and controlling access to these entities and their data to protect sensitive data and prevent unauthorized access. In this context, Identity and Access Management (IAM) systems are emerging as a critical solution. In this paper, we provide an overview of IoT technology and its main applications. Next, we review IAM systems, as well as the key concepts and challenges of applying these systems to the IoT environments.