## 4.17 Comment out text

It is useful to comment out text in the source document, which will not be displayed in the final output document. For this purpose, we can use the HTML syntax <!-- your comment -->. The comments will not be displayed in any output format.

Comments can span either a single line or multiple lines. This may be useful for you to write draft content.

If you use RStudio, you can use the keyboard shortcut Ctrl + Shift + C (Command + Shift + C on macOS) to comment out a line of text.