SSL/TLS

SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) are cryptographic protocols that encrypt data transmitted between a web browser and a server. When a website uses HTTPS instead of HTTP, it means an SSL/TLS certificate is active, and all data exchanged during the session, including form submissions, login credentials, and payment information, is encrypted so that it cannot be intercepted or read by third parties during transit. TLS is the current standard, but the term SSL persists in common usage.

An SSL/TLS certificate is issued by a Certificate Authority that verifies the identity of the domain owner. Let's Encrypt revolutionized the certificate landscape by offering free, automated certificates, making HTTPS accessible to every website regardless of budget. Most modern hosting providers and CDNs like Cloudflare now include automatic SSL provisioning as a standard feature. The certificate types range from Domain Validation, which simply confirms domain ownership and is sufficient for most websites, to Extended Validation, which involves thorough organizational verification and was historically displayed with a green address bar in browsers.

From a practical standpoint, HTTPS is no longer optional. Google has used HTTPS as a ranking signal since 2014, and modern browsers display prominent "Not Secure" warnings on any page served over plain HTTP, which directly undermines user trust and increases bounce rates. Beyond SEO and trust, HTTPS is a prerequisite for many modern web features including service workers, geolocation APIs, and HTTP/2 protocol benefits that improve page load performance. For web developers, ensuring SSL/TLS is properly configured, with correct certificate chains, HSTS headers, and no mixed content warnings, is a fundamental part of every deployment checklist.