The src/main/java part is a Maven convention: http://maven.apache.org/guides/introduction/introduction-to-the-standard-directory-layout.html http://maven.apache

The src/main/java part is a Maven convention: http://maven.apache.org/guides/introduction/introduction-to-the-standard-directory-layout.html http://maven.apache.org/guides/introduction/introduction-to-... This project has a "pom.xml" (Maven configuration file) in it's root directory, so it is using Maven. While you could use alternate folder structures with Maven, that requires configuration, whereas if you use the convention, Maven reads these folders by default. So if you also had a src/test/java folder, Maven would know that your unit tests are in that folder, and would automatically run the tests as part of the build. The org/resthub/todo part maps directly to the Java package (namespace), which would be "org.resthub.todo". As darklajid said, this is a language requirement. These deep folder structures can be annoying if you are using a regular file browser, but Java IDEs generally flatten out the packages, so that you see all packages all at once in a list, so you don't have to do a lot of expanding of subdirectories.