Static Members : static Member « Class Definition « Java Tutorial

1. Java Tutorial
2. Class Definition
3. static Member

1. Static members are not tied to class instances.
2. Static members can be called without having an instance.

The out field in java.lang.System is static.

public class MainClass {

  public static void main() {
    System.out.println("123");

  }

}

the method main(the entry point to a class) is static because it must be called before any object is created.