There are two types of repositories: local and remote. The local repository is maintained in your local machine by default at USER_HOME/.m2/repository. Anything that you build locally with the mvn install will get deployed into the local repository. When you start with a fresh Maven repository, there is nothing in it. You need to download everything from the simplest maven-compiler-plugin to all your project dependencies. A Maven build can be an online or offline build. By default, it's online unless you add -o to your Maven build command. If it's an offline build, Maven assumes that all related artifacts are readily available in the local Maven repository and if not, it will complain. If it is an online build, Maven will download the artifacts from remote repositories and store them in the local repository.