In order of decreasing difficulty, the titles are IGM, GMM, and IMM.
GMM titles will be awarded to the top 5 placed competitors who are not already GMMs who have achieved a total of 5,000 or more.
To achieve the IMM title, a competitor must achieve the three standards originally required for the GMM title: 1000 digits in one hour, 10 decks of cards in one hour, one deck of cards in 2 minutes or less.
Although there are masters from over two dozen countries, the vast majority are Chinese.
A full list of masters can be found on the International Association of Memory statistics website.