Source: https://uptimeify.io/resources/platform-and-support/glossary/hsts

# HSTS

> HSTS (HTTP Strict Transport Security) is a response header that tells browsers to only ever connect to a site over HTTPS, never plain HTTP.

HSTS prevents downgrade and cookie-hijacking attacks by removing the insecure HTTP option entirely. Monitoring that the header is present (and that HTTP correctly redirects to HTTPS) protects users and SEO.