Here are some different disk encryption technology.
For Windows:
- BitLocker: Built-in disk encryption for Windows Pro edition.
- Device encryption: Built-in disk encryption for Windows Home edition.
- VeraCrypt: Open source disk encryption for Windows, if you have Windows Home and an older computer that doesn't support BitLocker or device encryption.
For macOS:
- FileVault: Built-in disk encryption for macOS.
For Linux:
- LUKS is the built-in disk encryption for Linux. This Ubuntu Desktop tutorial has instructions on enabling encryption.