Apple has used combinations of metal, plastic, and glass to shape and form its ideas of what a modern smartphone should look like throughout the history of the iPhone. Major redesigns with the iPhone 4 and iPhone 5 saw Apple push the boundaries of smartphone hardware, all while competitors were catching up. Now that the smartphone industry is moving to larger screens, Apple has been forced to respond with the iPhone 6 and iPhone 6 Plus. Read on to see exactly how Apple evolved its iPhone hardware over the years, in our history of iPhone.