[[MediaWiki]] has its own [[markup]], they call it wiki markup. This is the first lightweight markup I had experience with (if you do not consider PHPBB markup to be lightweight).

=> https://www.mediawiki.org/wiki/Help:Formatting => https://en.wikipedia.org/wiki/Help:Wikitext

= Why I don't like it

• Syntax for bold and italic. ''italic'' and '''bold'''. This is classic! This syntax comes from very first wikis. But it's bad: ** Easy to confuse '' and " when editing in proportional font. This alone is enough. ** Six characters in total for one of the most used emphases (bold) is kinda uh. ** Not available on the standard Russian keyboard layout.
• Headings have to be closed at the end: {

== heading ==

And they also haven't resolved the [[level 1 problem]]. }

• Indentation-based preformatted text.
• Inclusion of HTML tags such as <br> and pseudo-HTML tags such as <nowiki>.
• Support of inline styling. Sure, because of that there are Mediawiki wikis with //really good// visuals, but you know the problems.
• Ridiculous linking of namespaces File and Category.
• Two different syntaces for local links and external links: {

[https://example.org text after space]
[[article | text after bar]]

}

• List items are limited to one paragraph.
• The syntax for image insertion is the same as linking a text page, except it's different.
• Tables that are //so// strong they replace everything not supported by the markup.
• Magic words like __NOTOC__ and #REDIRECT.
• Wrong line-break logic.

And for some reason, on mature MediaWiki wikis, almost every page is filled with countless {{}}s.

= Why I like it Still much better than [[Markdown]].

• Bracketed links.
• Character-repetition-based list nesting.
• = for headings.
• Tables are useful.
• The colon element is cute.
• Good macros (called //templates//).