SSL stands for Secure Sockets Layer. Its successor is TLS (Transport Layer Security), but in the PostgreSQL world, and in most documentation, people still call it SSL out of old habit. Don’t let that confuse you. When someone says “SSL” in a Postgres context, they mean modern TLS-based encryption. Here’s the problem it solves. By default, when your application connects to PostgreSQL, everything travels across the network in plain text. Usernames. Passwords. Every query you run. Every row of data that comes back. If anyone can intercept that traffic, someone on the same network, a compromised internal service, they can read all of it. A basic packet sniffer is enough. No special skills needed.