Mastery Ranking, commonly abbreviated as MR, is a method of tracking how much of the game’s total content a player has experienced with points earned by ranking up Warframes, Weapons, Companions, and Archwings with Affinity and also successfully completing Junctions and nodes on the Star Chart.
Players can view their own Mastery Progress and Rank by hovering the cursor over their Avatar on the top left corner of the UI. The profiles and Mastery progress of the player and other squad members can also be viewed by clicking “Profile” under their equipment tab. These details of other players in chat or in communications can be viewed by selecting their name and clicking “Profile.”