Tim Cook told Apple employees on Monday that he was stepping down as chief executive, handing over to John Ternus on Tuesday after 15 years in charge. He will, however, stay on as chief executive for political affairs.
In an internal message titled 'Thank you,' seen by French news agency AFP, Cook struck a note of gratitude and emotion, focusing on Apple’s teams and corporate culture.
Echoing a phrase often associated with Steve Jobs, he said Apple had made it possible to “leave our mark on the universe.”
Cook, who took over as chief executive in October 2011, two months before the co-founder’s death, said he was “completely at peace” with his decision. From Tuesday, he will become executive chairman with responsibility for political affairs.
Praising his successor, Cook wrote: “Few people understand what it takes to create products that change the world the way John does.”
Ternus, an engineer who joined Apple in 2001, helped develop the iPhone, while Cook built his reputation through supply-chain expertise and corporate diplomacy.
Ternus is due to make his first public appearance as Apple’s new leader on 9 September at the company’s autumn launch event.

