- Keys are given to the current Head of Household in order to unlock their HOH Bedroom.
- Keys are given out at Nomination Ceremonies. If a House Guest pulls a key with their name on it they are safe. The two House Guests not given keys are then put up on the block for Eviction.
- Keys have also been frequently used during Endurance Competitions and contestants are prompted to hold onto their keys for as long as possible.
- Keys are also given to jury members with both names of the finalists written on them. The jury member then walks up to a Nomination Box and places the key in it, where they are pulled one by one.
In Big Brother 13, a new special kind of key was given out called the Golden Key. These keys were given out to whichever member of a duo survived Eviction. These houseguests could not be nominated or play in competitions until the Final 10, but could still cast Eviction votes.
In Big Brother 14 invations were given to the Houseguests before due to the opening night twist where one houseguest was evicted within hours of entering the house.