*{
  margin: 0;
  padding: 0;
 }
and
body,div,dl,dt,dd,ul,ol,li,h1,h2,h3,h4,h5,h6,pre,code,
form,fieldset,legend,input,button,textarea,blockquote,th,td,p...{
    margin:0;padding:0
}
the first is simple,and I like it.But why many big web sites use the second method
 
     
     
     
    