What does the acronym XMLNS stand for, what does XMLNS mean?

Posted December 6, 2004

I was reading an article today on the accessibility benefits of <tbody>, <tfooter>, etc. tags for definingsections of information for a visually impaired user. That is when I came across was the xmlns attribute of the html selector means.

XMLNS means “XML Name Space”. But you may ask, what is a name space? I can’t really answer that yet. My limited understanding is that it is the path to find the specs for an XML document that you have linked to an HTML page.

I you “view source” on my webpage in the top you will see when I declare my <html> selector the tag has an attribute call xmlns in it and it looks like this;

<html xmlns=”http://www.w3.org/1999/xhtml”>

I can’t totally explain, like I said what it is for, I just know that when I was developing this site, I needed it there to prevent a “bugs” mode from happening where the CSS markup didn’t act properly.

Why do I need to close certain elements in XHTML like the <img> and <meta> tags?

I also happened across a better explanation on why a closing tag is needed on certain selectors in the XHTML spec. When I say “close” I mean with a closing forward slash and bracket like this />.

HTML is a markup language and so is XML. So when you don’t “markup” some information like with an image tag like this;

<img src=”http://www.rotheblog.com/images/design/jenbio.jpg” alt=”Rotheblog Bio Image” />

Where there are no tags surrounding the image, it is a stand alone tag, you need to close it with a “/>“