Tim Cook announced in a public letter that he is stepping down from his role as CEO of Apple. "This is not goodbye," he wrote, in part, in the letter shared Monday, April 20. "But at this moment of transition, I wanted to take the opportunity to say thank you. Not on behalf of the company, this time, though there is a wellspring of gratitude for you that overflows inside our walls. But simply on behalf of me. Tim. A person who grew up in a rural place in a different time and, for these magical moments, got to be the CEO of the greatest company in the world.