This document lists the changes made between the different API versions.

Version 3 (>= WordPress 6.3)

• The post editor will be iframed if all registered blocks have a Block API version 3 or higher. Adding version 3 support means that the block should work inside an iframe, though the block may still be rendered outside the iframe if not all blocks support version 3.
• In WordPress 7.0, the post editor is planned to always work as an iframe, regardless of the apiVersion of registered blocks.
  Please refer to this migration guide to test your blocks in the iframe editor beforehand.

Version 2 (>= WordPress 5.6)

• To render the block element wrapper for the block’s edit implementation, the block author must use the useBlockProps() hook.
• The generated class names and styles are no longer added automatically to the saved markup for static blocks when save is processed. To include them, the block author must explicitly use useBlockProps.save() and add to their block wrapper.

Version 1

Initial version.