SSL/TLS certificates are digital documents that authenticate websites and enable encrypted connections. They're why you see "https://" and a padlock icon in your browser.
What is SSL/TLS?
SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols that secure internet communications. TLS is the modern successor to SSL, but people often use "SSL" to refer to both.
How Certificates Work
- Website owner requests a certificate from a Certificate Authority (CA)
- CA verifies the owner controls the domain
- CA issues a signed certificate
- Browser checks certificate when you visit the site
- If valid, encrypted connection is established
Types of SSL Certificates
Domain Validation (DV)
Basic certificates that verify domain ownership. Quick to obtain, suitable for most websites. Free options available (Let's Encrypt).
Organization Validation (OV)
Includes verification of the organization's identity. Shows company name in certificate details.
Extended Validation (EV)
Highest level of validation. Requires extensive verification. Previously showed green address bar (no longer in modern browsers).
What to Check
- Certificate is valid (not expired)
- Certificate matches the domain you're visiting
- Issued by a trusted Certificate Authority
- Uses modern TLS version (1.2 or 1.3)
- Strong cipher suite (AES-256, etc.)
Use our SSL Checker tool to verify any website's certificate status and security configuration.
Common SSL Errors
- Certificate expired: Site owner needs to renew
- Certificate name mismatch: Wrong domain or subdomain
- Untrusted CA: Self-signed or unknown issuer
- Mixed content: HTTP resources on HTTPS page