A SATA controller is a hardware component that manages the connection between a computer's motherboard and its storage devices, such as hard drives and solid-state drives. It uses the Serial ATA (SATA) interface, which allows for faster data transfer rates compared to older interfaces like PATA. SATA controllers can be integrated into the motherboard or exist as separate expansion cards. They support various features, including hot swapping, which allows users to replace drives without shutting down the system. Overall, SATA controllers play a crucial role in ensuring efficient communication between the computer and its storage devices.