Module path vs class path, named, automatic and unnamed modules

Java has two ways to tell the JVM where your code and libraries are. The class path (-cp or --class-path) is the traditional flat list of directories and JARs; the JVM searches it for classes by name, with no concept of dependencies or encapsulation. The module path (-p or --module-path) holds modules; the JVM reads each module's descriptor, checks that every requires is satisfied before starting, and enforces exports. Where a JAR is placed decides what kind of module it becomes.