Evan Williams who is one of the co-founders of Twitter is stepping down from the board after serving 12 years on the board. Williams notified his move via a series of Tweets. He serves as the current CEO of Medium and was also the CEO of Twitter at one point. “I’m very lucky to have served on the @Twitter board for 12 years (ever since there was a board). It’s been overwhelmingly interesting, educational—and, at times, challenging,” he tweeted.