[Questions] What are contributions and tribe mastery?

When comparing profiles there level, xp, snaps, ect... is shown, but what is the contributions stat?

When looking at tribes in your profile, there's this bar to the left of the tribe logo which says "Tribe Mastery Score x/100" when hovered over. This appears to be different than tribe level since /t/politics/ is level 7 but has a score of 0/100, yet /t/ideasforsnapzu is level 3 with a score of 2/100.