The Web Viewer plugin displays web and document formats in a viewer window: HTML and MHT pages, XML, Markdown (.md, .mdown, .markdown), SVG, and PNG images. Markdown files are rendered with GitHub-style formatting, including their images.
The plugin uses Microsoft Edge WebView2, which is part of Windows 10 and Windows 11. On older systems, install the Microsoft Edge WebView2 Runtime.
See the File Viewer section in Using Plugins for a description of basic work with plugin viewers.