This document provides an introduction to Prometheus, an open-source monitoring system for containerized and cloud-native applications. It discusses key features of Prometheus including its time series data model based on labels and metrics, pull-based collection mechanism, built-in service discovery, query language (PromQL), and integration with Grafana for visualization. The document also covers Prometheus' use of exporters to collect metrics, relabeling to add Kubernetes metadata to scraped metrics, recording rules to generate new time series, and federation and remote storage for scalability.