For as long as I’ve been validating web pages, I never realized that the closing </head> tag was optional in HTML. I feel as if I’ve missed the boat at times. 
While I’m all for trimming excess code, I just cannot for the life of me strip out closing tags because they are optional in HTML. I’d be concerned that something, somewhere would not parse the document correctly if I removed the closing </head> element.
Are my concerns unfounded?
