What Is an SSL Certificate?
An SSL (Secure Sockets Layer) certificate is a digital certificate that authenticates a website's identity and enables encrypted connections. When installed, it activates HTTPS, displaying a padlock icon in the browser. While SSL has been superseded by TLS, the term "SSL certificate" remains widely used.
How It Works
When a browser connects to a website with an SSL certificate, a TLS handshake occurs. The server presents its certificate, the browser verifies it against trusted Certificate Authorities (CAs), and they negotiate an encrypted session. All data transferred is then encrypted, preventing eavesdropping and tampering.
Why It Matters
SSL certificates are essential for security, user trust, and SEO. Google uses HTTPS as a ranking signal, browsers flag HTTP sites as "Not Secure," and regulations like GDPR require encryption for data in transit. Without SSL, login credentials, payment info, and personal data are transmitted in plaintext.
Common Issues
- Certificate expired or about to expire
- Incomplete certificate chain
- Certificate hostname mismatch
- Mixed content warnings on HTTPS pages
- Self-signed certificates not trusted by browsers
Diagnostic Tools
Monitor SSL Expiry
Get alerted before your SSL certificate expires to prevent downtime and security warnings.