Apple just revealed a big way Siri is going to take on Amazon Alexa

Apple wants you to talk to your Apple Watch.

With the latest version of WatchOS, Apple is opening up Siri to Apple Watch apps. Specifically, Apple Watch apps related to fitness, payments, hailing a ride, or sending messages.

So while Siri on the iPhone has been able to book an Uber, that hasn't been possible through the Apple Watch. It's still not possible yet, but the tools for developers to make it happen are now available.

Siri is one of a few virtual assistants battling for market share. Google has its Google Assistant, and Amazon has a virtual assistant called Alexa that has been recently embraced by hardware makers.

The conventional wisdom is that Amazon is currently winning the race to rule the market for virtual personal assistants.

Google and Amazon have been packing their personal assistant into speakers, Google Home and Amazon Echo, and Apple is rumored to be working on a similar product.

But Apple has the advantage of millions of watches already on people's wrists. The argument is that you don't need a speaker equipped with microphones if there's already something on your wrist. Plus, there are more Apple Watches out there than Amazon Echos, according to estimates.

If you're interesting in building Apple Watch apps with Siri, more information is on Apple's developer website.