What are Security Headers?
Security Headers are a relatively new way of protecting a site from malicious actors on the internet. Simply put, it tells your web browser the rules in which the site must play. Websites can chose the rules they wish to put in their Security Headers depending on what content is on the site.
This is an excellent way to protect your site, but is not straight forward for the layperson. You can check any site in the world with the link below.