Markdown is nothing but simple text plus some formatting within the text to allow for formatting for the websites.
Since it is simple text, one could use a notebook or text editor vs a Document formatting software such as Microsoft Word, HTML editors, or others to formatting the documents.
Example text in Markdown:
A link to the *Wikipedia* [page](https://en.wikipedia.org/wiki/Markdown) about the **Markdown**
The same text Formatted in HTML:
A link to the Wikipedia page about the Markdown.
As you can see the text Wikipedia is in italics because of an asterisk (*) before and after the word. Website link is in parenthesis whereas the link text is in square brackets. The work Markdown is Bold because it is surrounded by two asterisks (**).
That’s it!