html doctype adds whitespace?

Question

can someone please explain to me why having a doctype of

and

Answer 1

My suspicion is that the white space within the markup (e.g., the newlines and tabs that make the table code nicely legible) are at fault. I've encountered similar issues before, where space in the markup resulted in annoying space on the screen, even where it would appear not to matter (e.g., between