SSL/TLS Certificate
A digital certificate that proves a website's identity and enables encrypted HTTPS connections.
An SSL/TLS certificate is a digital document installed on a web server that does two things: it proves the server's identity (you are really connecting to example.com, not an imposter) and it enables encryption via HTTPS. Certificates are issued by trusted Certificate Authorities (CAs) like Let's Encrypt (free), DigiCert, or Cloudflare's Origin CA. They contain the domain name, the issuing CA, the expiration date, and a public key used for encryption. Expired or misconfigured certificates cause Cloudflare errors 525 and 526, and browsers will show security warnings.