Microsoft introduced Windows Phone 8.1, which will offer a high-density, personalized start screen. Users can now have three tiles across the device and can choose a background, instead of a solid color, for the tile backgrounds.
Microsoft also introduced Cortana at the Build conference, the company's first voice-activated digital assistant. Cortana has her own live tile on the start screen, which you can see here in the center. Cortana is still in beta, and experienced a few hiccups during the presentation.