Artifacts become available once you've Prestiged.
They are randomly generated boost items that you can equip, upgrade, reroll, or trash.
Artifacts will help you boost Skill Tree points and Ability levels!
The Artifact Menu can be found by tapping the Shield button in the lower middle and navigating to the third tab.
Active vs Inactive:
Artifact boosts to Abilities and Skill Tree may be Inactive if you do not have the Ability or Skill unlocked yet.
Once it is unlocked then the boosts will show as Active. Only Artifacts boosts showing as Active are effective.