Sixteen years later, is it still a silly question to ask the same question? On the back end for Pages, what is "Extra Content" and "Code Block" used for?
I can't find anything about it in the user guide.
They are means of providing "extra" stuff for your website.
Extra Content is simple HTML, Code Blocks can have PHP code within them.
Exactly what happens depends on the theme you are using. Search your themes and plugins for printCodeblock and print*ExtraContent. (The asterisk is news or page.)
I'm using the ZenPage theme.
If I enter a line of text in the ExtraContent section and click 'Apply' that text does not appear when I click 'View Page'. Presumably that means the ZenPage theme doesn't support ExtraContent?
Please be patient with me, I'm only a poor Windows user.
Yes, the Zenpage theme does not support the extracontent field for pages or news. Even if by it structure it would just display where the content display anyway.. So just enter everything in the main content field. But it supports Codeblock 1 for news articles and pages.
Same applies for extra fields on images like location and such as well. Some fields are meant to be used for custom things like own themes.