In every website, written blog, or anywhere you will deal with texts, you will need an easy way to format and style your work, and that is what the markdown syntax will help you do.
The easier the way of styling, the more it will be practical, with markdown, you only need to add some symbols to your text to style it and format it. The most popular symbols are # for headers, put your text between * text * for italic (without spaces), and between ** text ** for bold (without spaces). other symbols have other functions, You can see how easy it is.
GitHub.com has its own touch on markup as well, there you will find syntax for task lists, tables, referencing, mentioning, …etc.GitHub.com also provides an easy way to creat web pages, blogs and structured documentations. you can view some of the syntax on GitHub Guides