how to block website from loading in iframe?
For modern browser, need to enable X-Frame-Options in Header,The x-frame-options header can be implement through web server configuration settings.
You can view the X-Frame-Options in Header as like below image,
Reference: https://www.keycdn.com/blog/x-frame-options/
If your browser does not support it, then you will have NO clickjacking defense in place and can use HTTP Header Field X-Frame-Options,
<meta http-equiv="X-Frame-Options" content="deny">There are three possible values for X-Frame-Options:
DENY - The page cannot be displayed in a frame, regardless of the site attempting to do so.
SAMEORIGIN - The page can only be displayed in a frame on the same origin as the page itself.
ALLOW-FROM uri - The page can only be displayed in a frame on the specified origin.
As of April 2016 the accepted answer by Krish R no longer works. Most browsers now ignore the meta tag as recommended by RFC 7034.
The correct way to implement this header is to have it sent with the document by the server. See the mozilla documentation on X-Frame-Options for details.