BitLocker is a disk encryption feature included with certain versions of Microsoft Windows. It protects data by encrypting the entire drive, making it inaccessible without proper authentication, such as a password or a special key. This security measure is especially useful if a computer or device is lost or stolen, as it helps prevent unauthorized access to sensitive information stored on the device. BitLocker operates seamlessly in the background and can be managed by individuals or IT administrators, offering an extra layer of protection for both personal and business data.