“Infrastructure as Code” technologies are the network automation concept used in configuring network devices, allocating network resources, and deploying developed applications. By using machine-readable codes, various tasks that previously required time and effort can now be done dynamically with infrastructure as code tools. Although Infrastructure as Code is a technology that brings many advantages and is still at the beginning of its popularity, there are not enough resource in the literature. In this study, the key concepts of Infrastructure as Code technologies are discussed and infrastructure as code tools are systematically examined. The four most used Infrastructure as Code tools were examined in terms of management, language, data representation, code approach, stateful and stateless, architectural perspectives. Also, they were compared over these key concepts.