XHTML was created but XML codes can be sloppy, like a code can either be all caps or not and not closing the tag properly, the outcome stays the same. (jan 1, 1999 – jan 1, 2002)
Description:
https://blog.rackspace.com/internet-history-html-evolutionAdded to timeline:
Date:
jan 1, 1999
jan 1, 2002
~ 3 years