The process by which metrics are by monitoring systems can generally be divided into two approaches—push and pull. As we'll see in the following topics, both approaches are valid and have their pros and cons, which we will thoroughly discuss. Nonetheless, it is essential to have a solid grasp on how they differ to understand and fully utilize Prometheus. After understanding how collecting metrics works, we will delve into what should be collected. There are several proven methods to achieve this, and we will give an overview of each one.