# Observability

> Being able to tell what a running system is doing, and why, from what it emits.

- Level: Intermediate
- Topics: Cloud
- URL: https://tidbit.legios.com.ar/observability/
- In Spanish: [Observabilidad](https://tidbit.legios.com.ar/es/observability/)

**Observability** is how well you can understand what is happening inside a running system just by looking at the data it sends out. With good observability, when users say checkout is slow you can find out which service, which request and which database query is to blame, without adding new code and redeploying first.

It rests on three kinds of signals. **Logs** are timestamped lines describing events ("payment 4812 failed: card declined"). **Metrics** are numbers measured over time, like requests per second, error rate or memory use. **Traces** follow a single request as it hops across many services, showing how long each step took. Together they are called **telemetry**.

Classic monitoring answers questions you thought of in advance: is the CPU above 90%? Observability aims to answer new ones, which matters in cloud systems made of dozens of microservices, where failures are often strange combinations nobody predicted. **OpenTelemetry** is the open standard most tools now use to collect these signals, and products like Amazon CloudWatch, Datadog or Grafana store and display them.

## An analogy

A car's gauges tell you speed and fuel; a mechanic's diagnostic computer lets you ask why the engine stutters at 3,000 rpm. Monitoring is the gauges, observability is the diagnostic port.

## Keep in mind

- Understanding a system's inside from the data it emits.
- Three signals: logs (events), metrics (numbers over time), traces (one request's path).
- Monitoring checks known problems; observability helps with unknown ones.
- OpenTelemetry is the common open standard for collecting telemetry.

## Go deeper

- [Observability primer (OpenTelemetry docs)](https://opentelemetry.io/docs/concepts/observability-primer/)
- [Observability (software) on Wikipedia](https://en.wikipedia.org/wiki/Observability_(software))

## Related terms

- [Database](https://tidbit.legios.com.ar/database/): An organized store of data that programs can search and update safely.
- [CPU](https://tidbit.legios.com.ar/cpu/): The chip that runs your programs, one instruction after another, very fast.
- [Cloud computing](https://tidbit.legios.com.ar/cloud-computing/): Renting computers over the internet instead of buying your own.
- [Microservices](https://tidbit.legios.com.ar/microservices/): Building one application as many small services that each do one job.
- [Open standard](https://tidbit.legios.com.ar/open-standard/): A public rulebook anyone can follow, so products from different makers work together.
- [Amazon CloudWatch](https://tidbit.legios.com.ar/amazon-cloudwatch/): The dashboard and alarm system that watches everything running in your AWS account.
- [Port](https://tidbit.legios.com.ar/port/): The numbered door on a computer that says which program a connection is for.