An external drive is a portable storage device that connects to a computer or other devices via USB, Thunderbolt, or other interfaces. It allows users to store, back up, and transfer data easily. External drives come in various types, including hard disk drives (HDD) and solid-state drives (SSD), each offering different speeds and storage capacities. These drives are commonly used for expanding storage space, safeguarding important files, and transferring data between devices. They are compatible with various operating systems, such as Windows and macOS, making them versatile tools for both personal and professional use.