This document discusses using Micrometer to monitor applications. It begins with an introduction to Micrometer and examples of using it with Spring Boot to define metrics like timers, histograms and counters. It then covers integrating Micrometer with Prometheus to store metrics and Grafana for visualization. The document provides examples of visualizing different metric types in Grafana and recommends securing exposed metrics endpoints. It suggests Prometheus, Graphite or other databases to store metrics and discusses best practices like disabling unneeded endpoints and implementing security.