BitLocker is a built-in encryption feature in certain versions of the Windows operating system. It helps protect data on a computer by encrypting the entire hard drive, making it difficult for unauthorized users to access the information. This is especially useful for laptops, which are more likely to be lost or stolen. To use BitLocker, users need a compatible version of Windows and a Trusted Platform Module (TPM) chip, which enhances security. Once activated, it requires a password or a recovery key to unlock the drive, ensuring that only authorized users can access the data stored on the device.