SSL (Secure Sockets Layer) is a security protocol designed to encrypt data sent between a user’s device (such as a web browser) and a server over the internet. Although the term “SSL” is still widely used, modern secure websites actually use its successor, TLS (Transport Layer Security).
What SSL/TLS does
When you visit a website that starts with https:// instead of http://, SSL/TLS provides:
- Encryption: Prevents others from reading data exchanged between you and the website (such as passwords or credit card numbers).
- Authentication: Verifies that you’re communicating with the legitimate website, not an impostor.
- Integrity: Ensures that data isn’t altered while it’s being transmitted.
How it works (simplified)
- Your browser connects to a website using HTTPS.
- The website sends its SSL/TLS certificate.
- Your browser verifies that the certificate is valid and trusted.
- The browser and server securely agree on encryption keys.
- All further communication is encrypted.
Example
Without SSL/TLS:
- Data travels as plain text.
- Someone on the same network could potentially intercept and read it.
With SSL/TLS:
- Data is encrypted.
- Even if intercepted, it appears as unreadable ciphertext.
SSL certificate
An SSL certificate is a digital certificate that:
- Confirms the website’s identity.
- Contains the website’s public encryption key.
- Is issued by a trusted Certificate Authority (CA).
Why people still say “SSL”
Although SSL versions (SSL 2.0 and SSL 3.0) are obsolete and considered insecure, the term “SSL” remains common. In practice, when people say “SSL certificate” or “SSL encryption,” they almost always mean TLS.
Summary
- SSL = Secure Sockets Layer (obsolete)
- TLS = Transport Layer Security (current standard)
- HTTPS = HTTP + SSL/TLS encryption
- SSL/TLS protects your data by providing:
- 🔒 Encryption
- ✅ Authentication
- 🛡️ Data integrity
In short, SSL/TLS is the technology that makes secure web browsing possible and is what gives websites the padlock icon in your browser.