A Headless CMS is a backend only content management system which works as a content repository and gives access to this content via REST (or GraphQL) services.

In traditional CMS, you have the following core subsystems:

• Content creation and management.
• Publication workflow.
• Content delivery.
• Analysis and monitoring.

Headless CMS focuses just on content creation and publication workflow. It is your application's responsibility to get the content and display it in an appropriate way based on your users' needs, devices they use, and the channels they operate on.

Advantages of Headless CMS:

• No tight coupling between business applications and CMS, resulting in flexibility that allows you to choose whatever technology and framework you like for your application.
• Headless CMS are usually much easier to deploy and use.
• Ability to easily integrate new channels, as we are not blocked by the functionalities available in a CMS.
• Nicely fits into microservice-based solution landscapes.
• Improved scalability and security due to dividing responsibilities of authoring and delivery, delivery can be separately scaled, and the authoring part can be completely hidden and not accessible to the outside world behind company firewalls.

Disadvantages of Headless CMS:

• Content authors are not able to preview how created content will look in the applications from the inside CMS.
• The analytical capabilities and content personalization features of a full blown CMS cannot be used and must be developed somewhere else.