Built into MediaWiki, permitting features like the blue highlighing on a selected footnote.
Template based.
No technical features, uses normal text.
Placement of note
Inside tags in the middle of the article.
At the end of the article, with a tag in the middle of the article.
Inside parentheses in the middle of the article.
Repeated references
Permits "named references" so we don't have to write the same reference information multiple times. Uses, however, a technology by which all footnotes to the same reference name have the same number, meaning that footnotes appear in a strange style unique to Wikipedia.