Like any other part of an HTML document, style sheets can have comments. A comment does not affect code; comments only add notes or give guidance to anyone viewing your code. You can include comments in the style element in the head of an HTML document or in an external CSS file, as shown in Code 2.29.
Code 2.29. You can use comments to add useful notes to a page without interfering with the code.
To include comments in a style sheet: