HTML Document type and XML namespace
I understand that in order to instruct the browser how to handle HTML page I need to specify a DOCTYPE... For a page that i built with HTML5 I used the following:
<!DOCTYPE html>
When i am viewing othe开发者_Python百科r sites that are using the same DOCTYPE, there is an additional definition inside the <html> tag, such as:
<html dir="ltr" xmlns="http://www.w3.org/1999/xhtml">
What does the xml namespace do that it is needed inside the HTML tag in addition to the DOCTYPE definition?
Thanks!
Joel
If the xmlns attribute is set, it's a XHTML (XHTML5) document.
This indicates a HTML5 document:
HTTP-Header Content-Type: text/html
<!DOCTYPE html>
<html>
And this indicates a XHTML5 document:
HTTP-Header Content-Type: application/xhtml+xml
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
If the webpage is using XHTML5 an does not have the xmlns attribute, it wont be displayed properly (Firefox would display the XML-DOM instead of the page).
HTML5 isn't XML, so the informations in the html tag aren't needed
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