Monitoring tells you when something is wrong. Observability tells you why.
Traditional monitoring tracks predefined metrics and fires alerts when thresholds are crossed. That works until something breaks in a way you didn't anticipate. Observability goes further. You can look at a system's external outputs and understand its internal state, even for problems you didn't plan for.
In Azure, that covers the full stack: infrastructure, application code, and services.
The three pillars
Metrics: Numeric measurements over time. CPU usage, request rate, error count, latency percentiles. Azure Monitor collects metrics from VMs, databases, App Services, and most other Azure resources. You build dashboards and set alerts on top of those metrics. This is where you catch performance problems early.
Logs: Detailed records of events, errors, and state changes. Azure Log Analytics gives you centralized log storage and querying with KQL. Microsoft Sentinel adds threat detection on top. When something breaks, logs give you the full story.
Traces: Distributed tracing tracks a request as it moves across services. In a microservices system, a single user request might touch five services. Azure Application Insights shows you the end-to-end transaction, where latency comes from, and which service is the bottleneck.
Telemetry integration: Azure services emit telemetry by default. You can instrument your application code with the Application Insights SDK or OpenTelemetry. OpenTelemetry is vendor-neutral, so you're not locked into Azure tooling if requirements change.
Practices I follow
Define the metrics that matter before you get paged at 2am. Know your SLOs. Set alerts based on those, not arbitrary thresholds. Centralize logs rather than SSHing into boxes and grepping around. Instrument services with distributed tracing from the start; it's painful to retrofit later. Build runbooks for common alerts so whoever is on call knows what to do. Review observability data regularly, not just during incidents.
The goal is to catch problems before users report them and resolve them in minutes instead of hours.