The main role of a system architect in IT is to design and oversee the architecture of complex systems, ensuring they meet specific requirements or business goals. System architects analyze both technical and business needs, creating blueprints for software, hardware, and networking infrastructures. They address scalability, security, and integration into existing systems while collaborating with various teams to ensure that architecture aligns with overall strategy. Their expertise guides the development process and helps in identifying potential risks and challenges throughout the system's lifecycle.