Digitization and technological transformation in providing various services have become a goal for many countries in light of the current digital revolution to implement the concept of a smart city. Given the great importance of the smart city concept by researchers, the overriding concern is how to maintain data security and user privacy. These two criteria can or directly represent the strengths and weaknesses of such technology projects. This paper included a comprehensive study of the smart city, its concept and components. The research also included a detailed study of the most important applications included in smart city services and their working mechanisms and uses. The diversity of applications and services provided under the smart city environment is proof of the importance of this model. The paper also reviewed the security risks of data in all stages of work, data collection, data transfer and processing. Finally, the paper reviewed the five most important technologies used in a smart city to maintain information security and data privacy, their advantages, their internal methodology and algorithms. In the end, this paper aims to give a clear picture of all the details of the smart city and the technologies used for the purpose of ensuring information security and data privacy.