[[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: {
```mediawiki
== 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//).