First of all, I'm speaking of webpage referral. Second, let me
quote Wikipedia: The misspelling referer originated in the
original proposal by computer "scientist" Phillip Hallam-Baker
to incorporate the field into the HTTP specification. The
misspelling was set in stone by the time of its incorporation
into the standards document Request for Comments (RFC) 1945;
document co-author Roy Fielding has remarked that neither
"referrer" nor the misspelling "referer" were recognized by the
standard Unix spell checker of the period. "Referer" has since
become a widely used spelling in the industry when discussing
HTTP referrers; usage of the misspelling is not universal,
though, as the correct spelling of "referrer" is used in some
web specifications such as the Document Object Model.  Hallam-
Baker, Phillip. "Re: Is Al Gore The Father of the Internet?"
alt.folklore.computers, 2000-09-21  Fielding, Roy. "Re: Referer:
(sic)." HTTP-wg, 1995-03-09 It seems even the W3C isn't
completely consistent: - http://validator.w3.o