A USB 3.0 to SATA adapter allows you to connect a SATA hard drive or SSD to a computer via a USB port. This enables you to use the SATA drive as an external storage device, for tasks like data transfer, backups, or using it as a bootable drive. These adapters typically support both 2.5-inch and 3.5-inch SATA drives, and many are backward compatible with USB 2.0.