A datapad is used to hold information such as audio recordings, videos and other forms of data. In Aliens vs Predator 3 (2010), Karl Bishop Weyland has possession of an executive datapad which had extra features, such as having an emergency transmitter.
The Rookie/player is able to collect datapads throughout the game for an achievement and for audio diary recordings which can be accessed in the main menu. These recordings help explain the game's backstory/plot.