A bus controller is a crucial component in computer systems that manages data transfer between the central processing unit (CPU) and other devices, such as memory and input/output devices. It ensures that data is sent and received in an orderly manner, preventing conflicts and ensuring efficient communication across the system's bus, which is the pathway for data. The bus controller operates by coordinating the timing and control signals needed for data transmission. It can be found in various architectures, including those using the PCI (Peripheral Component Interconnect) or USB (Universal Serial Bus) standards. By managing these processes, the bus controller helps maintain system stability and performance.