Markdown is a text-to-HTML conversion tool for web writers. Markdown allows you to write using an easy-to-read, easy-to-write plain text format, then convert it to structurally valid XHTML (or HTML).

https://daringfireball.net/projects/markdown/

TiddlyWiki and Markdown share some formatting rules eg: inline code and code blocks but WikiText also offers advanced functions like transclusions and macros