Use case for '&' in Less

gistfile1.less

/**
 * defaults.less
 */

div.my-class-name {
  padding: 15px; 
 
  form {
    padding: 10px;    
  } 
}

/**
 * app-view.less
 */
#app-view {
  div.my-class-name {
    &, form {
      padding: 0;
    }
  }
}