India, Sept. 1 -- On Monday, Tim Cook bid farewell to Apple - the company where he spent nearly three decades and led as CEO since 2011. Cook paid a tribute to founder Steve Jobs and praised Apple staff as "extraordinary" as he passed the baton to incoming CEO John Ternus.

"We have made it possible to leave our 'dent in the universe,' as Steve once described it," Cook wrote in the memo on his last day on the job.

(Also read: Tim Cook's last day as Apple CEO: Read his full memo to employees)

Apple co-founder Steve Jobs hired Tim Cook in 1998. By 2005, Cook was promoted to chief operating officer. He took over as CEO just weeks before Jobs died from pancreatic cancer.

Under Cook, Apple has become one of the most valuable companies in th...