Amazon
The update will make Alexa available via a microphone icon within the Amazon app. Tap that, and the assistant will do many of the things it can do on an Amazon Echo speaker. You can ask it to search for things to buy and add to your shopping list, naturally, but the e-commerce giant also says it'll be able to read Kindle books, stream music from Amazon's own services, control select smart home products (but not smart door locks), check the news and weather, answer random questions, or use one of the many third-party "skills" that work with the assistant.
It's worth noting that Amazon already makes a dedicated Alexa app for iOS - that doesn't let you use the full assistant, but it is used to handle settings and download skills for iPhone-owning users of other Alexa devices. That app will continue to be used for any settings changes with the updated Amazon app. The company did not specify why it's bringing the assistant to its main app instead of the Alexa app, but the former should introduce it to a much wider audience.
Amazon
The update is just the latest in a string of moves Amazon has made to make Alexa more ubiquitous than its rival voice assistants. Though its Echo speakers are Alexa's most popular conduit, the service is showing up in a growing number of third-party apps and smart devices. In January, Chinese phone maker Huawei announced that it plans to incorporate Alexa into its Mate 9 Android phone. The number of skills developed for Alexa has exploded in the past year, too, though past studies suggest most people tend to use the assistant for simpler tasks.
Nevertheless, all of this comes at a time where fellow tech giants like Google, Apple, and Microsoft continue to develop and promote their own smart assistants. Though none of these helpers are at a point of being very good, they are thought to be the next major way people interact with their computing devices.
Amazon has to hope this move will make more people comfortable with using its horse in the race, but given that Apple's Siri assistant is still baked into iOS as a whole, it's unlikely to take up too much turf.