Use of the <noscript> tag:
The <noscript> tag defines an alternate content for users that have disabled scripts in their browser or have a browser that doesn't support script.
The <noscript> element can be used in both <head> and <body>.
When used inside the <head> element: <noscript> must contain <link>, <style>, and <meta> elements.
The content inside the <noscript> element will be displayed if scripts are not supported, or are disabled in the user's browser.
Tip: It is also a good practice to use the comment tag to "hide" scripts from browsers without support for client-side scripts (so they don't show them as plain text):
In HTML 4.01, the <noscript> tag can only be used inside the <body> element.
In HTML5, the <noscript> tag can be used both inside <head> and <body>.
In XHTML, the <noscript> tag is not supported.
The <noscript> tag also supports the Global Attributes in HTML.
HTML tutorial: HTML Scripts