You can now have deep, meaningful conversations with Cortana without even unlocking your device -- if you're a Windows 10 Insider, that is.
Microsoft dropped a big update to its flagship OS in one of the most recent Windows 10 Insider Preview builds (Build 14328), but regular users won't see these changes until the Windows 10 Anniversary Update, which will likely drop around the end of July 2016.
One of the new features revealed in the Insider Preview Build 14328 is Cortana on the lock screen -- Cortana now lives on the lock screen and you can ask her to do things like create reminders, schedule appointments and perform calculations all without unlocking your device. If you ask her to do something that requires launching an app, she'll prompt you to unlock your device, but otherwise this is a pretty handy hands-free feature.
Here's how to turn it on (you'll need a computer running Windows 10 Insider Preview Build 14328 or later):
Open Cortana and go to Settings.
You're done! Now you can use Cortana -- either by saying "Hey, Cortana" (if you have it enabled) or by tapping the Cortana icon on the lock screen.