Cortana is a disembodied voice on WP8 based on the Halo character YouTube/calloftreyarch "We are focused on making Windows 10 the most loved version of Windows ever," Satya Nadella told financial analysts on Thursday, something he's said many times before.

And there's one thing he thinks is really going to do it for people: Microsoft's virtual assistant, Cortana.

Cortana will be a feature of the operating system, helping you perform tasks on your PC (search for documents, keep track of your calendar), and in Microsoft's new browser, Spartan, helping you perform tasks on the Internet (book travel, annotate web pages.)

And all you have to do is talk to it.

Nadella said:

Cortana, that’s perhaps the thing that’s going to change personal productivity even most and especially with Windows 10 and how Cortana comes to Windows, both to the browser as well as to the Start [menu]. I think it completely changes what personal productivity software means from a day-to-day experience.

And, by the way, Microsoft is reportedly working on bringing a version of Cortana to iPhone and Android. So you won't have to buy a Windows phone (or even a Windows computer) in order to use it.

We expect to hear a lot more about this next week at Microsoft Build, the company's big developer conference being held in San Francisco.

If you haven't had a chance to see Cortana in Windows 10, here's a short video to give you a taste.