Various methods to implement the prompt function of text box in html

<style type="text/css">
.in_search {
border:1 none;
color:#999999;
float:left;
font-size:14px;
height:18px;
line-height:18px;
margin:3px 2px;
width:253px;
}
</style>
<input name="q" class="in_search" onfocus="if(this.value=='Please enter what you want to enter'){this.value='';}" onblur="if(this.value==''){this.value='Please enter what you want to enter';}" type="text" value="Please enter what you want to enter"/>