Artifacts provide a permanent boost once you have uncovered them! Each Artifact is uncovered in a different way, and each gives a different bonus for different things.
 
The bonus from Artifacts applies to all normal continents, so not the Event Mines, Mainland Mines, or Impossible Island.
 
You can uncover Artifacts in any order, and the active bonus from uncovered Artifacts will show on the mine overview on your world map.
 
Please note that some Artifacts require you to collect your Boosts and not use them anywhere else so that you can uncover them! If you uncover an Artifact by using Boosts, you will not be able to see them in your Boost Inventory anymore.