From Halopedia, the Halo wiki
Powerups are gameplay items that enhances player traits for a duration. They are commonly featured in multiplayer maps in Halo: Combat Evolved, Halo 2, Halo 3, Halo 4, Halo 2: Anniversary, Halo 5: Guardians, and Halo Infinite. Power-ups can be added via Forge in Halo 3, Halo: Reach, Halo 4, Halo 2: Anniversary, and Halo 5: Guardians. They are also featured in the campaign of Halo: Combat Evolved and Halo 2. In Halo Infinite, power-ups act more like equipment. They can be stored in the players inventory and activated at will.
List of powerups
The following is a list of power-ups throughout the Halo first-person shooter titles.
List of buffs
The following is a list of buffs that are similar to power-ups but are only applied when carrying mythic weapons in Halo 5: Guardians. As long as the weapon is equipped and has ammo/charge, the buffs will be applied.