Introduction
There’s no definitive Markdown specification so to learn its syntax you have to hunt around a little.
John Gruber devised the original Markdown syntax which he documented on his Daring Fireball site
The Wikipedia article documents attempts to standardise markdown. These have been unsuccessful so de facto standards have emerged based on influential users such as Github.com
John Gruber deliberately kept his original syntax small. He prioritises readability and leaves more complicated constructs, such as tables, to be implemented via their HTML tags.