id selector is introduced using "#", which has the same effect as the "." of the class selector. Example: #div{} Let's do a specific experiment: html:
<!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>认识html标签</title> <style type="text/css"> </style> </head> <body> <h1>勇气</h1> <p>三年级时，我还是一个<span id="stress">胆小如鼠</span>的小女孩，上课从来不敢回答老师提出的问题，生怕回答错了老师会批评我。就一直没有这个勇气来回答老师提出的问题。学校举办的活动我也没勇气参加。</p> <p>到了三年级下学期时，我们班上了一节公开课，老师提出了一个很简单的问题，班里很多同学都举手了，甚至成绩比我差很多的，也举手了，还说着："我来，我来。"我环顾了四周，就我没有举手。</p> </body> </html>
css:
#stress{
color:red;
}Rendering:
In many ways, ID selectors are similar to class selectors, but There are also some important differences:
1. Set id="ID name" for the label instead of class="class name".
2. The ID selector is preceded by a pound sign (#) instead of an English dot (.).
