I\'m using markdown to edit this question right now. In some wikis I used wiki markup. Are they the same thing? Are they related? Please explain. If I want to implement one
Markup is a general term for content formatting - such as HTML - but markdown is a library that generates HTML markup. Take a look at Markdown.
Markdown and the markup used in Mediawiki (the wiki software that powers Wikipedia) is not the same.
They're related in the sense that both are less verbose ways of entering html (with some added features), but I doubt that they are related to each other in any other sense.
If you want to implement Markdown on your site just Google Markdown + your favourite platform/language and you'll likely to find a library that does it for you.
If you want to implement Mediawiki's markup you probably need to look round for better ones (like Markdown).
Mark-up is a term from print editing - the editor would go through the text and add annotations (i.e. this in italic, that in bold) for the printers to use when producing the final version. This was called marking up the text.
A computer mark-up language is just a standardised short-hand for these sorts of annotations.
HTML is basically the web's standard mark-up language, but it's rather verbose.
A list in HTML:
<ul>
<li>Item one</li>
<li>Item two</li>
</ul>
Markdown is a specific markup language, having its own simple syntax.
A list in Markdown:
* Item one
* Item two
Both of these will work in your stackoverflow posts.
Markdown can't do everything HTML can, but both are mark-up languages.
Markdown is a play on words because it is markup. "Markdown" is a proper noun.
Markup is just a way of providing functionality above plain text. For example: formatting, links, images, etc.