On Tuesday, the newest version of WordPress, 4.4, was released. It features a number of standard updates that are common in new WordPress versions, such as a new theme and code and performance improvements.
But the most notable update in WordPress 4.4 is the inclusion of infrastructure for the WordPress REST API. That API, which is inspired by and based on the standalone WP REST API plugin developed to help developers "access WordPress data in a standardised, interoperable manner," may be one of the most highly-anticipated WordPress features ever.
Inclusion of the WP REST API in WordPress core has been discussed since 2014 and notable companies, including the New York Times and Bloomberg, were quick to adopt the WP REST API in their production applications.
With infrastructure for the WordPress REST API now in place, WordPress developers are in position to add the API's core endpoints. According to WordPress creator Matt Mullenweg, this "is targeted for an upcoming release."
Once those endpoints are available, WordPress developers will be able to use WordPress as an application backend without any additional plugins. That will give them the opportunity to implement their own front-ends using whatever technologies they chose. Automattic, Mullenweg's company, did exactly this when it built a new version of WordPress.com and many more WordPress developers will likely be doing the same in the near future.