An element that can contain other elements or content
<a href="[<http://example.com>](<http://example.com/>)">A link element contains text.</a>
An element that cannot contain anything else
<br/>
<img/>
<p>
Imagine there's no Heaven<br/>It's
easy if you try <br/>No hell below
us <br/>Above us only sky
</p>
To make an image, you need 3 parts:
<img src="<https://stock.adobe.com/search?k=github+logo>"
alt="Github Logo"/>
More reading: http://osric.com/chris/accidental-developer/2012/01/when-should-alt-text-be-blank/