WYSIWYG (pronounced wiz-ee-wig) is an acronym for “What You See Is What You Get”. It helps identify an an interface that allows user input resulting in an output that is rendered in a similar way. For example; a word processor application interface might resemble a piece of paper,so when printed the user can see how the output will appear.
When building webpages using HTML & CSS, the underlying code does not resemble the visual appearance rendered in a web browser. Editing the page at the code level requires a level of knowledge most website editors do not possess. Instead a CMS might be connected to create editable page structure that more closely resembles the rendered webpage.
Synonyms
What You See Is What You Get
Further reading
Wikipedia