A block WordPress theme is a type of theme that utilizes blocks to construct and customize every part of a website, including headers, footers, navigation menus, and content. Block themes are designed for the visual editing experience of Full Site Editing (FSE), allowing users to build and modify their website without needing to write any code. 

Block themes are built from the ground up to work seamlessly with the WordPress Block Editor. This integration allows for an unprecedented level of customization directly from the editor. Users can manipulate not only the content but also the layout and structure of their pages