The main function of server virtualization in cloud computing is to optimize resource utilization by allowing multiple virtual servers to run on a single physical server. This technology enables organizations to consolidate their IT infrastructure, leading to reduced hardware costs and improved energy efficiency. Virtualization also allows for enhanced flexibility and scalability, as resources can be allocated dynamically based on real-time demand. Moreover, it simplifies management and maintenance, reducing downtime and providing businesses with a more resilient and efficient computing environment.