xmlns attribute for html?

I'm making a website and I'm wondering what I'm supposed to put as the value for the xmlns attribute.

<html xmlns="?">

Thanks in advance.

Update:

An explanation of the xmlns attribute would be nice also.

The sites I've checked say it "specifies the xml namespace for a document"

..but I have no idea what xml namespace means.. =P

Update 2:

I know I don't need it (well I do now), but I still I have to learn about it and include it for an assignment.

Update 3:

On that Wikipedia site.. I don't even understand the first sentence. Like what's it mean by "uniquely named elements and attributes"?

Simple terms would be nice.

2 Answers

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