I understand you should use class for multiple elements and ID for a single element. 

However they can both be used on multiple elements. 

So are these two elements (class and id) identical in what they can actually do (as opposed to what they are supposed to do) *or am I missing something*?

For example I've created both Classes and ID's and applied them both to mutliple elements on my fiddle: <http://jsfiddle.net/4qyoyfwq/> (coded below):

```css
#blueid {
    color:blue
}
.greenclass {
    color:green
}

p#purple {
    color:purple
}

p.yellow {
    color:yellow
}
```

```html
<p id="blueid">Hey! I am blue id</p>
<p class="greenclass">I am green class</p>
<b id="blueid">Yup, also blue id!</b>
<br />
<br />
<b class="greenclass">Yet I am green class</b>
<br />
<p id="purple">I am purple id</p>
<p class="yellow">I am yellow class</p>
```

So why the two different types?