A group of statements enclosed by { and }. : block « Statements « SCJP

1. SCJP
2. Statements
3. block

The statement block is treated as a single statement when used with selection, 
iteration, and other statements.
  
public class MainClass {
  public static void main(String[] argv) {
    {
      int x = 1;
      int y = 2;
      x += y;
    }

  }
}