Markdown influenced by Textile
History
Markdown was inspired by pre-existing conventions for marking up plain text in email and usenet posts, such as the earlier markup languages setext (c. 1992), Textile (c. 2002), and reStructuredText (c. 2002).In 2002 Aaron Swartz created atx and referred to it as "the true structured text format". Gruber created the Markdown language in 2004, with Swartz acting as beta tester, had the goal of enabling people "to write using an easy-to-read and easy-to-write plain text format, optionally convert it to structurally valid XHTML (or HTML)."Its key design goal was readability, that the language be readable as-is, without looking like it has been marked up with tags or formatting instructions, unlike text formatted with 'heavier' markup languages, such as Rich Text Format (RTF), HTML, or even wikitext (each of which have obvious in-line tags and formatting instructions which can make the text more difficult for humans to read).
Gruber wrote a Perl script, Markdown.pl, which converts marked-up text input to valid, well-formed XHTML or HTML and replaces angle brackets (<, >) and ampersands (&) with their corresponding character entity references. It can take the role of a standalone script,  a plugin for Blosxom or a Movable Type, or of a text filter for BBEdit.