What does mvn install in maven exactly do

Have you looked at any of the Maven docs, for example, the maven install plugin docs?

Nutshell version: it will build the project and install it in your local repository.

As you might be aware of, Maven is a build automation tool provided by Apache which does more than dependency management. We can make it as a peer of Ant and Makefile which downloads all of the dependencies required.

On a mvn install, it frames a dependency tree based on the project configuration pom.xml on all the sub projects under the super pom.xml (the root POM) and downloads/compiles all the needed components in a directory called .m2 under the user's folder. These dependencies will have to be resolved for the project to be built without any errors, and mvn install is one utility that could download most of the dependencies.

Further, there are other utils within Maven like dependency:resolve which can be used separately in any specific cases. The build life cycle of the mvn is as below: LifeCycle Bindings

1. process-resources
2. compile
3. process-test-resources
4. test-compile
5. test
6. package
7. install
8. deploy

The test phase of this mvn can be ignored by using a flag -DskipTests=true.