What is “X-Content-Type-Options=nosniff”?

I am doing some penetration testing on my localhost with OWASP ZAP, and it keeps reporting this message: The Anti-MIME-Sniffing header X-Content-Type-Options was not set to ‘nosniff’ This check is specific to Internet Explorer 8 and Google Chrome. Ensure each page sets a Content-Type header and the X-CONTENT-TYPE-OPTIONS if the Content-Type header is unknown I … Read more