The goal of this paper is to explain how cloud computing, mobile computing, and edge computing contribute to the development and operation of smart cities in order to enhance the quality of life both in health and urban planning, among which energy management is included. Cloud computing provides scalability and on-demand resources for urban simulations, while mobile computing allows real-time information sharing with citizens. Edge computing allows data processing to be done locally, reducing network congestion. The paper covers, among other discussions, some of the challenges that arise in integrating these technologies, including bandwidth limitation, network optimization, service quality, and data security. This analysis shows how smart cities can effectively leverage advanced computing to create sustainable and livable urban environments.