Halo 2 Terminals

In Halo: Master Chief Collection in the Halo 2 Anniversary Campaign Levels you can find these terminals that if you press you will be able to watch a video that goes into the lore and backstory surrounding the Halo universe.
You can get Halo: Master Chief collection on X-box or PC and your progress can be saved between them. If you don't want to buy the whole game, you can get it for free if you have x-box game pass.

Link to buy game on Microsoft store: https://www.xbox.com/en-us/games/store/halo-the-master-chief-collection/9ntm9hxnlszx