The update adds handy tabs to the Notepad. You can start a new markdown file by clicking the File menu and clicking the New ...

With Markdown, writing HTML-formatted documents is as easy as writing plain text. Software developers use it, but so do many others. The Markdown text format makes it easy for people—not only ...

With plain text, you don't need to figure out italics or boldface. Your editor can't do that if you wanted to. "Plain text" means plain text. It's encoded in ASCII or increasingly in Unicode.