A storage controller is a device or software that manages data storage devices, such as hard drives and solid-state drives. It acts as an intermediary between the storage devices and the computer system, ensuring that data is read and written efficiently. Storage controllers can be found in various forms, including RAID controllers and SAS controllers, which help improve performance and data redundancy. These controllers can be integrated into a computer's motherboard or exist as separate hardware units. They support different storage protocols, such as SATA and NVMe, allowing for compatibility with various types of storage media. By optimizing data flow, storage controllers enhance overall system performance and reliability.