Meaning
Secure Sockets Layer (and modern TLS); the standard cryptographic protocol for establishing an authenticated and encrypted link between web browsers and servers.
Three examples from work
Certificate renewal
DevOpsOur SSL certificate was automatically renewed through Let's Encrypt.
LeadExcellent, no risk of browser security warning screens for our users.
Security audit
AuditorDoes your web application force SSL across all HTTP endpoints?
DevYes, we enforce HSTS with automatic 301 redirects to HTTPS.
API troubleshooting
Frontend DevThe mobile app throws an SSL handshake failure in our staging environment.
DevOpsThe intermediate certificate chain was missing on the staging load balancer; fixing it now.
Pronounce each letter: 'S-S-L'. Modern protocols technically use TLS, but industry terminology continues to use 'SSL' interchangeably for certificates and HTTPS encryption.