Then some genius realized computers and displays were now powerful enough to show you what the page looked like while you created it. This was called What You See Is What You Get (WYSIWYG).
In the early days of web page creation you had to do much the same thing, code everything by hand, then view it in a browser to see what it looked like. Naturally when we started getting editors that showed you the page as you created it they also received the WYSIWYG nom de plume.
And now you know more than you wanted to.