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Starting with WordPress 5.9, released at the beginning of 2022, the Full Site Editing (FSE) concept became available to all WordPress users. FSE is a collection of new WordPress features that focus on styling blocks and using blocks for all parts of a website, not only the content area.
WordPress Full Site Editing themes — otherwise referred to as simply WordPress block themes — come packed with lots of useful features and advantages.
Undoubtedly, the main advantage is the ability to fully edit the page: header, footer, sidebar, and other areas. No coding skills required and no more messing with complicated theme files!