html tags don't format in Javascript

this isn't javascript it's php.

You may notice that I close my HTML tags inside the script with a backslash before the forward slash in the closing tag. This is a requirement of the specification (and can cause the HTML validator not to validate your page if you forget it), although all browsers will understand if you omit the backslash.

However, since you can write HTML with script, you can write style or even script tags with it, making one script import another. If you omit the backslash on any </script> tags that you are writing with the script, the browser will read that as the closing tag for the current script, and your script will fail.