public static class Person {
      public int age = 20;

      public void adjustAge(int age) {
          this.age = age + 20;
          System.out.println("The age in adjustAge() is " + age);
I am just confused, can someone kindly advise me why we should have this.age instead of keeping it just as age? I thought static variables can be called anywhere in a program because they belong to the class, but if a variable is non-static, then we need to use this. I thought the variable age is a static variable as it was created with the class. Can someone please clarify the reason why we use this.age as well as whether age variable a statis or non-static? Thanks in advance.