WHOIS
An SSL certificate (technically, in almost all modern cases, a TLS certificate — "SSL" stuck around as the common name) is what makes the padlock icon appear in a browser's address bar. It does two specific things: encrypts the connection between a visitor and the server, and cryptographically proves the server is who it claims to be for that specific domain.
What it actually verifies
A certificate is issued by a Certificate Authority (CA) and confirms: this specific domain name controls the private key that matches this certificate. That's it. It does not verify that the website is trustworthy, safe, or legitimate in any broader sense — a certificate is genuinely easy to obtain for any domain, including ones registered specifically for phishing.
The trust chain, briefly
Your browser doesn't trust a website's certificate directly — it trusts a small set of root Certificate Authorities, which have signed intermediate certificates, which in turn sign the website's actual certificate. If every link in that chain checks out and the certificate hasn't expired or been revoked, the browser shows the padlock.
Domain Validation vs. Organization/Extended Validation
Most certificates today are Domain Validated (DV) — they only confirm control of the domain, issued automatically within minutes. Organization Validated (OV) and Extended Validation (EV) certificates involve actual verification of the requesting organization's identity, though modern browsers no longer visually distinguish EV certificates the way they once did.
How to check a certificate yourself
Our SSL Checker gives a quick overall status and also shows the full certificate detail — issuer, validity dates, Subject Alternative Names, and more; SSL Expiry Checker focuses specifically on the expiry countdown.