---
title: "Concepts | Grafana documentation"
description: "Learn about concepts basic to tracing."
---

# Concepts

Distributed traces provide a way to monitor applications by tracking requests across services. Traces record the details of a request to help understand why an issue is or was happening.

Tracing is best used for analyzing the performance of your system, identifying bottlenecks, monitoring latency, and providing a complete picture of how requests are processed.

To use the Grafana Traces Drilldown app, you should understand these concepts:

- [Concepts](#concepts)
  
  - [Rate, error, and duration metrics](#rate-error-and-duration-metrics)
  - [Traces and spans](#traces-and-spans)

## Rate, error, and duration metrics

The Traces Drilldown app lets you explore rate, error, and duration (RED) metrics generated from your traces by Tempo.

Expand table

| Useful for investigating                 | Metric   | Meaning                                                        |
|------------------------------------------|----------|----------------------------------------------------------------|
| Unusual spikes in activity               | Rate     | Number of requests per second                                  |
| Overall issues in your tracing ecosystem | Errors   | Number of those requests that are failing                      |
| Response times and latency issues        | Duration | Amount of time those requests take, represented as a histogram |

For more information about the RED method, refer to [The RED Method: how to instrument your services](/blog/2018/08/02/the-red-method-how-to-instrument-your-services/).

## Traces and spans

A trace represents the journey of a request or an action as it moves through all the nodes of a distributed system, especially containerized applications or microservices architectures. This makes them the ideal observability signal for discovering bottlenecks and interconnection issues.

Traces are composed of one or more spans. A span is a unit of work within a trace that has a start time relative to the beginning of the trace, a duration, and an operation name for the unit of work. It usually has a reference to a parent span in a trace, unless it’s the first span, also known as the root span. It frequently includes key/value attributes that are relevant to the span itself, for example, the HTTP method used in the request, as well as other metadata such as the service name, sub-span events, or links to other spans.

For more information, refer to [Understand your data](/docs/grafana-cloud/telemetry-signals/).