Characteristics
Hardware-based encryption when built into the drive or within the drive enclosure is notably transparent to the user. The drive except for bootup authentication operates just like any drive with no degradation in performance. There is no complication or performance overhead, unlike disk encryption software, since all the encryption is invisible to the operating system and the host computers processor.
The two main use cases are Data at Rest protection, and Cryptographic Disk Erasure.
In Data at Rest protection a laptop is simply closed which powers down the disk. The disk now self-protects all the data on it. Because all the data, even the OS, is now encrypted, with a secure mode of AES, and locked from reading and writing the data is safe. The drive requires an authentication code which can be as strong as 32 bytes (2^256) to unlock.
Read more about this topic: Hardware-based Full Disk Encryption