<div id = "number1">		#number1 {……;}	only one id with the same value in a page
	<div class = "number1">		.number1 {……;}
	<p id = "number1">		#number1 {……;}	only one id with the same value in a page
	<p class = "number1">		.number1 {……;}
	<span class = "name">Mary</span>		.name {……}