Bricks are the visually editable content blocks that you create to define your design system.
They constitute the core of React Bricks.
Bricks are just React components with 2 features that enable the "visual magic":
- They use the React Bricks visual components (like Text, RichText, Image, Repeater, File) in the JSX to allow direct visual editing
- They have a schema to define the behavior of the content block, for example the sidebar control that you want to make available to editors to change props of the React component
There is a full chapter of this documentation about Bricks.