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Bittocker is an encryption program $($i$.$e$.$ a conversion of information into a secret code$)$ available for anyone who has a machine running Microsoft Windows $($Pro or Enterprise editions$).$ This program presents users with BitLocker log$-$in when they first start$-$up their devices. This BitLocker log$-$in appears before they enter their own personal password.

Encryption prevents unauthorised users from extracting or retrieving data from a device in the event of theft loss. In order to access a device with a BitLocker program, the user must enter a correct recovery key $($i$.$e$.$ a numerical password$).$ These recovery keys are a lot harder to decrypt $($i$.$e$.$ to decipher$)$ than a typical personal password. Therefore, hackers are less likely to access a computer that has a BitLocker program installed.

There's some controversy with the BitLocker program. It does not contain a backdoor $($i$.$e$.$ a method to bypass encryption to gain access to a given device$)$ and law enforcement can't access these Microsoft devices without the recovery key. There's been cases of government agencies putting pressure on Microsoft to enable a backdoor, but Microsoft haven't implemented this for security reasons.