# java.base The `java.base` module is where all packages like `java.lang`, `java.util`, etc. are defined. This means it contains classes used by nearly every Java program like `java.lang.String`, `java.lang.Integer`, and `java.util.ArrayList`. Because of this, it is the only module you do not need to explicitly require in a `module-info.java` file. ```java module cool.code { // You can leave this line off // and it will still require java.base requires java.base; } ``` And when you have a file that makes use of "The Anonymous Main class," Java will also act as if you had a module import for `java.base`. This means that you don't actually need an explicit import for classes like `ArrayList`. So if a file has the following ```java void main() { var names = new ArrayList(); names.add("Him"); names.add("Jim"); names.add("Bim"); IO.println(names); } ``` It is equivalent to ```java import module java.base; class Main { void main() { var names = new ArrayList(); names.add("Him"); names.add("Jim"); names.add("Bim"); IO.println(names); } } ```