Ranked in these QuestionsQuestion Ranking
Designed to be easy for a human to enter with a simple text editor, and easy to read in its raw form.
Pro De facto standard
Markdown is ubiquitous. It's supported by nearly everything. The markup available in the common subset of all the many dialects isn't that rich, but it's usually enough to get the job done.
Pro Widely used
Markdown is quickly becoming the writing standard for academics, scientists, writers, and many more. Websites like GitHub and reddit use Markdown to style their comments.
You can convert HTML to Markdown or Markdown to HTML. You can use tools like pandoc to convert to other formats as well.
Pro Revision friendly
It is easy to track changes for markdown documents as compared to other formats like doc, html, etc. You only need to place your markdown documents under some version control system.
Con Bad support for table
It has poor support for table, while table is an important part of article.
Con Lacks a coherent standard
Lacks a coherent standard, just many semi-compatible dialects (MultiMarkdown, etc)
Con Bad support for larger documents
Works good for single file documents like READMEs.
Lack support for cross-references, TOCs, document index etc.
Con It doesn't support semantic markup