Contentful is a “headless” CMS. In other words, it’s a content management system with no display layer. They worry about building a backend that your content creators can easily use, and you query their API for JSON formatted data to integrate into your frontend.

API-first, not browser-first
All the created content is accessible via an API. Bring your content anywhere, display it as you like.

Scalable cloud, not on-premise setup
Your content is stored on our servers. They are fast, safe, secure, and we take care of all the maintenance.

Content-centric, not page-centric
Organize and structure the content your way. Build a custom content model instead of dealing with fixed, predefined templates.

Just the content, no presets or templates
Contentful delivers the content, and you design around it. We separate the content from presentation — it’s most flexible this way.

Source: Contentful: a developer-friendly, API-first CMS – Contentful