This document discusses code coverage tools and JaCoCo in particular. It summarizes that JaCoCo is an open-source Java code coverage library that collects execution data for Java applications and libraries. JaCoCo can collect data both offline from Java byte code or online by instrumenting Java applications dynamically. The document compares JaCoCo to other code coverage tools and outlines JaCoCo's integrations, metrics, and features to help developers test code coverage.