Microsoft's "digital assistant", the Halo-inspired AI Cortana, will be available on iOS and Android devices in in addition to Windows Phone when Windows 10 launches this summer.
As detailed on the Windows Blog, Cortana will exist on third-party phones as a separate app that will work in conjunction with your "Phone Companion" app on PC. As such, you'll still need computer with Windows 10 to kick off the process, but iOS and Android devices will be able to sync with Microsoft's operating system back home.
"The 'Phone Companion' app on the PC will help you install the Cortana app from the Google Play or Apple App Store onto your phone so you'll be able to take the intelligence of Cortana with you, wherever you go," corporate vice president Joe Belfiore explained.
Examples given include having Cortana remind you to pick up groceries based on the geographic location of your phone, or tracking flights. "Everything in Cortana's Notebook will show up across all your devices and any changes you make on one device will be reflected when you use Cortana on any of your other devices. The Cortana companion app will help you complete tasks you begin on your PC wherever you are, on your phone."
There are a few perks that you'll miss out on using Cortana as a separate app - as opposed to on Windows Phone where she's native to the hardware. You won't be able to interact with Cortana when you have other apps open, for example, and you won't be able to access her by just saying "hey Cortana." You'll have to actually use your hands to touch the icon, like a baby's toy.