A SCSI Controller is a hardware component that manages communication between a computer and its storage devices, such as hard drives and tape drives, using the SCSI (Small Computer System Interface) protocol. It allows multiple devices to connect to a single controller, enabling efficient data transfer and management. The SCSI controller can be integrated into the motherboard or exist as a separate expansion card. It supports various SCSI standards, which define the speed and capabilities of the connected devices. This versatility makes SCSI controllers popular in servers and workstations that require high-performance storage solutions.