Before the iPhone Duo: these brands had already invested in foldable phones

Apple has officially entered the foldable smartphone market with the Wednesday launch of its high-end device, the iPhone Duo. Featuring a book-style format with a 5.4-inch exterior screen, the release marks the baptism of fire for Apple's new head, John Ternus.

The launch takes place against a backdrop of a global chip shortage that has driven up device prices across the industry. While Apple's entry represents a milestone for the company, it arrives several years after the foldable category began developing and after competitor brands had already established a presence in the market.