Terminals are objects found in Halo 3, Halo: Combat Evolved Anniversary and in Halo 4. Conceptually based upon similar terminals in Bungie's earlier Marathon game series, the Terminals fill the player in on the Halo backstory.
 Halo 3
- Main article: Halo 3 Terminals
The Terminals in Halo 3 are in textual format, similar to the Terminals in Marathon. They are a continuation of the Iris alternate reality game used as viral marketing for Halo 3. They clarify a great deal of the Iris storyline by naming the authors of different messages and by explaining the circumstances of the original firing of the Halo Array. The Terminals follow the stories of the Librarian and the Didact, Forerunner logs of the Flood attacks, and Mendicant Bias's progression into rampancy.
 Halo: Combat Evolved Anniversary
- Main article: Halo: Combat Evolved Anniversary Terminals
The Terminals in Halo: Combat Evolved Anniversary feature fully-animated cutscenes instead of text like in Halo 3. Most of them are logs narrated by 343 Guilty Spark and expand on the history of Installation 04. They also have connections to the stories of The Forerunner Saga and Halo 4.
 Halo 4
- Main article: Halo 4 Terminals
The Terminals return within Halo 4, and they feature fully-animated cutscenes, like the terminals in Anniversary.