有没有人帮我解释下这段代码
<!-- start main-->
<div class="main_bg">
<div class="business">
业务领域 BUSINESS
</div>
<div class="wrap w_72">
<div class="grids_1_of_3">
<div class="grid_1_of_3 images_1_of_3">
<img src="img/pic1.png" >
</div>
<div class="grid_1_of_3 images_1_of_3">
<img src="img/pic2.png" >
</div>
<div class="grid_1_of_3 images_1_of_3">
<img src="img/pic3.png" >
</div>
<div class="grid_1_of_3 images_1_of_3">
<img src="img/pic4.png" >
</div>
<div class="grid_1_of_3 images_1_of_3" style="background: none">
<img src="img/pic5.png" >
</div>
<div class="clear"></div>
</div>
</div>
</div>
<!-- start main-->