SSL/TLS certificates are digital certificates used to secure communication between web browsers and servers on the World Wide Web. They enable encrypted connections, protecting sensitive data during transmission. These certificates verify the authenticity of websites and establish trust, contributing to web security and search engine rankings.

This certificate is not valid This certificate and its chain is not valid, it signifies potential security and trust issues. An invalid SSL certificate could mean it has expired, been revoked, or not issued by a trusted Certificate Authority (CA). Additionally, an invalid certificate chain may indicate missing or misconfigured intermediate certificates, making it impossible to establish a secure connection to the website. In such cases, web browsers will typically display warnings to users, cautioning them about potential security risks, and it's advisable to avoid interacting with such websites to protect sensitive data from potential threats.