Look out, Siri: You no longer need an Echo, Echo Dot, or a Tap to use Amazon's voice assistant, as it's now available on iOS devices. But before you start saying "Hey Alexa" into your iPhone, here's what you need to know about what it can and can't do, whether you have it, and how to use it.
Ed. Note (6/27/18): Amazon has updated its Alexa app for iOS devices; you can now speak commands through the app.
1. Open the Amazon Alexa app.
2. Tap the Alexa icon in the bottom of the app. Not surprisingly, you can't say "Hey Alexa" to wake your iPhone, as you would with Siri. You don't need to press and hold the button. Just a tap will do.
3. The first time you use this feature, you will have to grant Alexa some permissions on your iOS device. Press Allow.
4. Another window will appear, asking you to confirm your decision. Press Allow.
5. The next window (which will also only appear the first time you use this feature) gives you some examples of things you can ask Alexa. Press Done at the bottom.
6. You will see a dark transparent window with a thin blue band at the bottom, as well as suggestions for things that you can ask. If you want to cancel your request, press the blue X.
At this point, you can ask Alexa anything you would of any other Alexa-enabled device, from turning on your smart lights to ordering items online to random questions about the universe. For example, when I asked Alexa "why is the sky blue," she responded by talking about how light refracts through the atmosphere.