Markup

Because text files are just a stream of letters and numbers, there isn't an easy way to tell the formatter to mark a specific section as bold or italic, marking a section as a block quote or epigraph, or where to put the headings.

To add that information, a “markup” language is used to annotate the text to indicate the desired formatting. These days, the most common markup language is Markdown, but there are others.

• Markdown

Choosing Markup

Markup, like programming languages, can be a personal choice. Some folks lightweight systems like Markdown (this is *italic*) while others prefer ones that use control code such as LaTeX (this is \em{italic}).

I prefer Markdown because of it popularity. There are a lot of tools and libraries that work with it. There are plenty of examples across the internet which means it also has many tutorials that I could point someone to to learn the specifics.