Apple has named John Ternus as its new chief executive to replace Tim Cook, who is stepping down after 15 years of leading the technology giant.

Ternus, currently the head of hardware engineering who has been at Apple for 25 years, will take over on 1 September and Cook will become executive chairman.

Cook has been chief executive of Apple since 2011 after co-founder Steve Jobs resigned for health reasons, shortly before his death.

Cook will stay as chief executive through the summer to work with Ternus on the transition after which he will assist with certain aspects of the company, including engaging with policymakers around the world.

Cook's decision to step away from the chief executive role follows months of speculation that Apple was looking for a successor. He described the job as the greatest privilege of my life and during his tenure he led the company to become one of the most valuable in the world.

In 2018, Apple became the first public company to be valued at $1 trillion and is now worth $4 trillion. Cook described Ternus as a visionary executive with the mind of an engineer, the soul of an innovator and the heart to lead with integrity and honour. He is without question the right person to lead Apple into the future, Cook added.

Ternus emerged as a favourite to replace Cook last year, after another long-time executive, chief operating officer Jeff Williams, left the company.

During his quarter century at Apple, Ternus has worked on every major product the company has released, including every generation of the iPad, many generations of the iPhone, and the launch of AirPods and the Apple Watch. He also oversaw the transition of Mac computer processors to Apple's own silicon.

Ternus also worked under Jobs. In a statement, he referred to Cook as his mentor.

I am filled with optimism about what we can achieve in the years to come, Ternus said.

'Differentiation'

Naming a leader who comes from a product and hardware background may allow Apple to emerge from a constant criticism of Cook's tenure, that it was no longer innovative enough.

While Cook oversaw a four-fold increase in Apple's yearly profit, with a massive expansion in products sold around the globe, its product line has remained largely static. Analyst Dipanjan Chatterjee praised Cook's financial stability but noted he hadn't given the company a product like the iPhone for sustained future success.

The appointment of Ternus shows Apple is looking for differentiation in its products and critics highlight the need for innovation beyond the iPhone.

With Ternus at the helm, Apple is expected to invest more in new products, including foldable phones and wearables. The tech giant has also faced criticism for being slow to embrace AI technology but now may pursue deeper AI integration into its hardware.

Tim Cook's legacy will remain significant, as he is remembered for refining and scaling Apple into a powerhouse, as well as for launching the Apple Vision Pro, a virtual reality headset that did not gain much traction.