When creating or editing a note, you will see the text "Supports Markdown Syntax" at the bottom right. Markdown is intended to be used to format the text within a note. For example, if you wish to format bulleted lists, headings, bold or italicized copy, paragraphs, blockquotes, lists, etc., you can do so utilizing the markdown syntax language. The language is comprised entirely of punctuation characters. But when viewed or published, a Markdown-formatted document appears as plain text, without looking like it's been marked up with punctuation, tags or formatting instructions.
The"Supports Markdown Syntax" text also links to a resource document further explaining what Markdown:Syntax language is and how to use it.