SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) are protocols that encrypt data transmitted between a web server and a browser. An SSL/TLS certificate is a digital certificate that enables this encryption and verifies the website's identity.
What SSL/TLS Does
Encryption
Data is encrypted during transmission. Even if intercepted, it's unreadable without the decryption key.
Authentication
The certificate verifies you're connected to the real website, not an impostor.
Data Integrity
Ensures data isn't modified during transmission.
How SSL/TLS Works
- Browser connects to server and requests secure connection
- Server sends its SSL certificate
- Browser verifies the certificate with a trusted authority
- They agree on encryption method
- Encrypted communication begins
This "TLS handshake" happens in milliseconds.
HTTP vs. HTTPS
HTTP: Unencrypted. Anyone can read data in transit. HTTPS: Encrypted with SSL/TLS. Data is protected.
You can see HTTPS in your browser's address bar, often with a padlock icon.
Types of SSL Certificates
Domain Validated (DV)
- Verifies domain ownership only
- Issued in minutes
- Cheapest (often free)
- Good for: Most websites
Organization Validated (OV)
- Verifies organization identity
- Takes a few days
- Moderate cost
- Good for: Business websites
Extended Validation (EV)
- Rigorous verification process
- Shows organization name in some browsers
- Most expensive
- Good for: Banks, high-trust sites
Wildcard Certificates
Covers all subdomains: *.example.com
Multi-Domain (SAN)
Covers multiple domains in one certificate.
Getting SSL Certificates
Free Options
- Let's Encrypt: Free, automated, widely supported
- Cloudflare: Free SSL with their CDN
- Hosting providers: Many include free SSL
Paid Options
- Comodo/Sectigo
- DigiCert
- GlobalSign
Why SSL Matters
Security
Protects sensitive data (passwords, credit cards, personal info).
Trust
Users expect the padlock. Missing it raises suspicion.
SEO
Google uses HTTPS as a ranking factor.
Compliance
Many regulations (PCI-DSS, HIPAA) require encryption.
Browser Warnings
Chrome and others warn users about non-HTTPS sites.
SSL Certificate Management
- Monitor expiration dates
- Auto-renewal when possible
- Test after installation
- Ensure all resources load over HTTPS