BitLocker is a proprietary encryption program for Windows that allows users to secure their files and folders by encrypting the drive that the data is stored on. After the BitLocker application has been turned on, every file that is saved to the drive is automatically encrypted. BitLocker To Go is used to encrypt portable storage devices like external hard disks and thumb drives.
In order for BitLocker to be used, the computer's hard drive must be partitioned at least twice. There must be a system partition that contains all the start-up files and an operating system partition that BitLocker will encrypt. The system partition is not encrypted. Windows automatically installs these partitions; however, if the computer lacks a system partition, BitLocker can automatically create one using 200 MB of the available disk space. The system partition is not listed in the computer folder and does not have a drive letter.
BitLocker encrypts drives with 256-bit or 128-bit encryption; which is enough to guarantee that data remains safe in the event that the hard drive is stolen or misplaced. BitLocker protects data from various forms of offline attacks. With BitLocker, even if someone has physical access to the hard drive, the data on the drive cannot be read or altered.