Pro Gamers is not a clan, it's an open group of players that anyone can join, as long as they're interested in utilizing teamwork while gaming. Pro Gamers participants are encouraged, but not required, to the end of their name and play on Pro Gamers endorsed servers. By adding PG to the end of your name you're easily recognizable by other Pro Gamers participants, so they can engage in teamwork with you; and by playing on Pro Gamers endorsed servers you are much more likely to encounter other Pro Gamers participants, and have the best gaming experience as a result.