Project Object Model (POM)

The Project Object Model (POM) is a fundamental concept in the [[Apache Maven]] software project management and comprehension tool. Defined in an [[Extensible Markup Language|XML]] file named pom.xml at the root of a Maven project, the POM includes information about the project and various configuration details used by Maven to build the project.

The POM file specifies the project's configuration, including its dependencies, plugins, goals, version, and other settings necessary for Maven to build the project. Maven encourages a standard directory layout for projects, which can be customized in the POM file. This standardization facilitates understanding and maintaining the project.

One of the key features of the POM is to define the dependencies required by the project. Maven automatically handles the downloading and updating of dependencies declared in the POM. The POM file configures plugins and defines specific goals to be achieved during the build process, such as compilation, testing, packaging, and deployment.

It includes project information like the name, version, URL, developers, and contributors. This metadata can be useful for documentation and project reports. POM allows defining different build profiles for various development environments. For example, you can have separate profiles for development, testing, and production.

In multi-module projects, a parent POM can manage common configurations for all sub-modules, promoting reusability and easier project management. The POM file defines how the project's build lifecycle is managed, including phases like compile, test, package, install, and deploy.

Maven POM supports project versioning. Development versions are often marked as SNAPSHOTs, indicating that they are under active development. The POM can specify repositories from which to fetch dependencies or to which to deploy artifacts.