An audit trail is not a log. It's a tamper-evident, time-ordered record of who did what, when, and why. Most teams build this wrong. Here is how to do it correctly using OpenTelemetry and append-only storage.

Regulated industries need observability too. A guide to building telemetry pipelines that satisfy GDPR, HIPAA, SOC 2, and PCI DSS requirements — covering data minimisation, retention mandates, audit trails, and what each framework actually requires.