Audio Diaries (or Audio Logs) are the main narrative device of the BioShock series. They were recorded by citizens of Rapture, either as notes for themselves or as messages for other residents. Picking up an Audio Diary stores it automatically in the associated in-game menu while offering to play it by entering the key associated to the last one found. However, a handful of plot-crucial diaries throughout the games play automatically as soon as they are picked up.