Maven is a build automation tool used primarily for Java projects that handles dependencies and builds. It downloads libraries and plug-ins from repositories and manages a local cache. The POM (Project Object Model) XML file contains project configuration information like dependencies, directories, and plugins and is used by Maven to build the project. Maven is useful when projects have many dependencies, dependencies change frequently, or continuous integration, testing, and documentation generation are needed.

1. Maven
Why do we need Maven?
If you are working on Java projects then most of the time you need dependencies.
Dependencies are nothing but libraries or JAR files. You need to download and add
them manually. Also, the task of upgrading the software stack for your project was
done manually before Maven. So there was a need for a better build tool that would
handle such issues.
This where Maven comes into the picture. Maven can solve all your problems related
to dependencies. You just need to specify the dependencies and the software version
that you want in pom.xml file in Maven and Maven will take care of the rest. So now
let us try to understand what exactly Maven is.
What is Maven?
The Maven project is developed by Apache Software Foundation where it was
formerly a part of the Jakarta project. Maven is a powerful build automation tool that
is primarily used for Java-based projects. Maven helps you tackle two critical aspects
of building software -
 It describes how software is built
 It describes the dependencies.
Maven prefers convention over configuration. Maven dynamically downloads Java
libraries and Maven plug-ins from one or more repositories such as the Maven Central
Repository and stores them in a local cache. The artifacts of the local projects can also
be updated with this local cache. Maven can also help you build and manage projects
written in C#, Ruby, Scala, and other languages.
Project Object Model(POM) file is an XML file that contains information related to
the project and configuration information such as dependencies, source directory,
plugin, goals, etc. used by Maven to build the project. When you execute a maven
command you give maven a POM file to execute the commands. Maven reads the
pom.xml file to accomplish its configuration and operations.

2. When should someone use Maven?
1. If there are too many dependencies for the project.
2. When the dependency version update frequently.
3. Continuous builds,integration,and testing can be easily handled by usingmaven.
4. When one needs an easy way to generate documentation from the sourcecode, compiling
the sourcecode, packagingcompiled code into JAR files or ZIP files.
The POM
The pom.xml file is the core of a project's configuration in Maven. It is a single
configuration file that contains the majority of information required to build a project
in just the way you want. The POM is huge and can be daunting in its complexity, but
it is not necessary to understand all of the intricacies just yet to use it effectively.
 Once you create the projectthen you will seethe project structureof your Maven project.
Here you can see the followingthings –
1. pom.xml
2. src and target
3. src/main/java
4. src/test/java
5. Maven dependencies
1. <project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
2. xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">
3. <modelVersion>4.0.0</modelVersion>
4.
5. <groupId>com.mycompany.app</groupId>
6. <artifactId>my-app</artifactId>
7. <version>1.0-SNAPSHOT</version>
8.
9. <properties>
10. <maven.compiler.source>1.7</maven.compiler.source>

3. 11. <maven.compiler.target>1.7</maven.compiler.target>
12. </properties>
13.
14. <dependencies>
15. <dependency>
16. <groupId>junit</groupId>
17. <artifactId>junit</artifactId>
18. <version>4.12</version>
19. <scope>test</scope>
20. </dependency>
21. </dependencies>
22. </project>