CSS: about div id and div class - html

Question

Good day guys! I'm a newbie here and I'm just wondering how to use div id and div class. Let's say for example, I want to have many div boxes in my site with all the same styles in each box. Is this the right thing to do? Please enlighten me.
HTML:
<div id="body">
<div id="box1" class="style"></div>
<div id="box2" class="style"></div>
<div id="box3" class="style"></div>
//(and so on)//
</div>
CSS:
.style {
//(put elements here)//
}

Answer 1

There is not really a right thing to do as everything depends on the situation and circumstances.
Why would you think that this would be the "wrong" thing to do? This cuts down on the amount of code you have to write, so it is favorable, correct?
You can also use the IDs you have to override styles for the <div>s individually:
.style {
color: red;
}
#body1 {
color: blue;
}
Due to the fact that elements, IDs, and classes each have difference selector precedence, I advise against using anything except for classes and psuedo-classes no matter how attractive other prospects may seem. If you're disciplined about it, your CSS will be easier to update later on. The above example would work exactly the same if body1 were a class instead of an ID (I would suggest using IDs to identify unique elements for DOM manipulation, though).
I would also follow the W3C's advice when picking class names for elements and using them in your HTML:
...authors are encouraged to use values that describe the nature of the content, rather than values that describe the desired presentation of the content.

Answer 2

ID's are unique:
-Each element can have only one ID
-Each page can have only one element with that ID
Classes are NOT unique:
-You can use the same class on multiple elements.
-You can use multiple classes on the same element.

Answer 3

Yes that would work. Though the id's would not be needed if all you want to do is apply the same style to all 3.
http://www.w3schools.com/tags/att_global_id.asp
http://www.w3schools.com/tags/att_global_class.asp

Answer 4

Yes You can do that if you want to have same style applied to all divs than you can definitely use class to apply styling to divs. If your div is going to be different than others than you can can probably use id which will allow you to access that div through javascript also.

Answer 5

If it is only styling then id is not really required and you need not to give class name if it is same class for all child divs.
HTML
<div id="body">
<div></div>
<div></div>
<div></div>
</div>
CSS
#body div {
background:red;
width:100px;
height:100px;
display:inline-block
}
DEMO

Answer 6

You can use "class" in many div's but you can use "id" in only one place. Because ID should be unique in each page.
<div id="body">
<div class="mystyle"></div>
<div class="mystyle"></div>
<div class="mystyle"></div>
//(and so on)//
</div>
<style>
.mystyle{color:#000;}
<style>

Answer 7

You can use this
<div id="demo">
<div class="box test"></div>
<div class="box test"></div>
<div class="box test"></div>
</div>
CSS:
#demo
{
margin:0;
padding:0;
}
.box
{
Width:100px;
height:50px;
background:red;
}
.test
{
color:white;
}
you can apply two class.