Question: is tier 1 the highest?
Answer: Tier 1 is the lowest and Tier 8 is (currently) the highest. The Tiers are designated by Roman numerals (I, II, III, IV, V, VI, VII, VIII = 1, 2, 3, 4, 5, 6, 7, 8) etc. Based on your Tier, you can then enter into ranked tournaments with bigger prize pools and often restrictions on who can participate.