New categories of handhelds have emerged and been rapidly adopted, such as e-readers —Amazon's Kindle and Apple's iPad. Wireless hotspots to connect to the Internet are everywhere in urban areas and on trans-portation lines, and access to high-speed 3G and 4G net-works has made interoperability a standard, as you also read in Chapter 1. Consumer and enterprise apps for mobile computing and commerce continue to expand the capabilities of this in-demand technology.