In 2011, Apple's Siri was the talk of the town, an electronic assistant that could interpret free-form voice queries and respond with relevant information most of the time. Although Android had voice-based search at the time, it was nothing like Siri.
Since then, Android has caught up. And with Windows Phone 8.1, Microsoft introduces Cortana -- a surprisingly good voice response technology, capable of handling free-form requests as accurately as Siri and Google Now. Although technically still in beta, Cortana comes off as a polished final product, not a first try.