Metrics are the core resources that the Prometheus stack ingests to provide you with useful information. Understanding them correctly is essential to fully utilize, manage, or even extend the realm of possibilities this stack has to offer. From data to information, and finally to knowledge, metrics are here to help you.

In brief, the following topics will be covered in this chapter:

• Understanding the Prometheus data model
• A tour of the four core metric types
• Longitudinal and cross-sectional aggregations