# Introduction

Code metrics are used in:

* Rules to raise issues, for example, when a certain level of complexity is reached for a function in the code. See [rules](https://docs.sonarsource.com/sonarqube-community-build/quality-standards-administration/managing-rules/rules "mention") of Understanding rules page for more information.
* Quality gate definition, for example, you can set a condition on the total number of raised issues in the code. See [introduction-to-quality-gates](https://docs.sonarsource.com/sonarqube-community-build/quality-standards-administration/managing-quality-gates/introduction-to-quality-gates "mention") for more information.
* The mode of your SonarQube Community Build instance, either [mqr-mode](https://docs.sonarsource.com/sonarqube-community-build/instance-administration/analysis-functions/instance-mode/mqr-mode "mention") or [standard-experience](https://docs.sonarsource.com/sonarqube-community-build/instance-administration/analysis-functions/instance-mode/standard-experience "mention"), will determine which code metrics you see in the UI.

You can use different tools in the SonarQube Server to monitor and compare your project code metrics.

{% hint style="info" %}
If you’re using an external monitoring system, you can retrieve the metric values through the [web-api](https://docs.sonarsource.com/sonarqube-community-build/extension-guide/web-api "mention").
{% endhint %}

## Related pages <a href="#related-pages" id="related-pages"></a>

* [metrics-definition](https://docs.sonarsource.com/sonarqube-community-build/user-guide/code-metrics/metrics-definition "mention")
* [monitoring-project-metrics](https://docs.sonarsource.com/sonarqube-community-build/user-guide/code-metrics/monitoring-project-metrics "mention")
* [metrics-parameters](https://docs.sonarsource.com/sonarqube-community-build/instance-administration/analysis-functions/metrics-parameters "mention")