Create a box to share code???

How do I create one of those boxes on my site to share code? The box contains the code that people can past on their site. If I wanted to share code, image link, etc..

 

<xmp>
Code you wish to share.
</xmp>

Code (markup):

 

If your site must be compliant with web standards I'd recommend using

<textarea>
Code here
</textarea>

 

I figured <xmp> would be out-dated. Found it a few years ago.

 

I'd never heard about it before until today, had to Google it!