Apple deleted the smartphone's keyboard and buttons and let software be the interface

By 2006, the smartphone market's leaders — the BlackBerry, Palm Treo and Windows Mobile devices — all shared the same physical layout: a hardware keyboard occupying a third or more of the device's face, plus dedicated buttons and often a stylus, all fixed in place no matter which application was running. That fixed hardware was treated as a mark of seriousness for a business device, but it meant every phone carried the weight, cost and screen space of an input method most apps didn't actually need at any given moment.

Apple's team, developing the iPhone in secret, could have followed the category's own logic and added a slide-out keyboard alongside a touchscreen, as many rivals did. Instead Steve Jobs presented the decision as a binary at the iPhone's January 2007 unveiling, mocking existing phones for keyboards 'there whether you need them or not' and stylus-based input, and committed the device to touchscreen input and a single physical button.

Deleted the keyboard and let software redraw controls per app, so the interface became a different tool for each task.

Removing the keyboard freed the entire device face for a larger screen.

A software interface can redraw controls for each app, unlike fixed keys.

Multitouch gestures like pinch-to-zoom offered new interactions impossible with hardware.

The iPhone's responsive touchscreen made the software keyboard a convincing replacement.

When fixed hardware limits flexibility, consider removing it and letting software adapt to each task.

The iPhone sold out its first weekend on sale in June 2007 and remade the industry's default interface around touchscreens within years. Within several years nearly every phone manufacturer, including BlackBerry itself, abandoned physical keyboards for touchscreens, making software-defined input the default interface for a device category that had spent a decade assuming fixed hardware.