What is Observability?

Observability is the ability to understand the internal state of a system just by looking at its external outputs. Unlike traditional monitoring, which tells you whether something is wrong, observability helps you understand why it's wrong.

It's built on three pillars:

Logs: discrete, timestamped events (e.g., "User 123 logged in").

Metrics: numeric measurements over time (e.g., request latency, memory usage).