WYSIWYG stands for “what you see is what you get.” It describes visual editing that resembles the intended output. The resemblance can be useful, but it does not guarantee the published page matches the editor in every browser, viewport or medium.
Compare editing and output
A visual editor might let you select text and apply a heading style without writing markup. Inspect the published HTML to see whether it created a real heading or merely changed a paragraph’s font size. The visual appearance alone cannot tell you.
Check the constraints
The editor may use different fonts, a fixed-width canvas or styles that differ from the live site. Pasted content can add unexpected markup. Image alternatives, labels and reading order still need attention.
Exercise: create a short heading, paragraph, link and list in a visual editor. Publish or export a practice copy, then inspect the elements and test a narrow viewport. Compare the editor’s preview with the browser’s actual output.
Keep useful control
A visual editor can make common authoring tasks easier, while direct HTML and CSS offer more explicit control. Neither approach automatically produces good code or accessible content. Choose the tool that fits the authors’ tasks and provides a reliable verification path.
Read semantic HTML, heading structure and front-end design before treating a polished preview as the final result.
Sources
Reference 1 Reference 2 provide the technical details and current compatibility information.