Hah - The person
thinks a comment is mildly funny.
Haha - The person
does not think the comment is funny, but acknowledges your attempt humor.
Hahaha - the person
thinks the comment is funnier
than average, or is just more enthusiastic than those who normally say haha.
Hahahaha - The person
is just being excessive. Usually used
a friendship because an inside joke was just mentioned.
Haha is almost never used
to express actual laughter
occuring. For those circumstances, rofl, lmao, or a whole sentence about how the comment actually made one laugh