A headless CMS uses only the backend portion of the application. The frontend (think of this as the head) is removed. Then, the CMS functions as a content repository that delivers content in a format compatible with a variety of devices. This results in the ability to deliver content for websites, desktop applications, mobile apps, and other internet-connected devices from one data source.
On the CMS’s backend, content editors are still free to work with content in the usual fashion. However, with the freedom to choose the frontend software stack, the frontend could be anything. Developers are free to choose any tech stack for multiple types of devices or operating systems.
Headless CMSs aid in mobile development as well, delivering content to native mobile apps designed for different types of Android and iOS devices.
In this scenario, headless WordPress functions as a data server that sends JSON data via the WordPress REST API. The JSON data can be used in any application based on any programming language. This allows content to be served to multiple devices, each with its own frontend implementation.
With WordPress’s core functionality as a CMS available as a data source for any type of device, developers and content editors can repurpose any type of data that normally appears on a WordPress website. However, as a data source, headless WordPress is not limited to only WordPress content like post content, comments, media, and so forth. Developers can also use the WordPress core and database to build innovative, modern frontend applications that take advantage of the CMS’s time-tested dynamic content capabilities. All the while, content editors have the ability to manage content as usual in the WordPress backend.