[publicdebates]

Human history is full of cases where silly mistakes became precedent. HTTP "referal" is just another example.

I wonder if there's a wikipedia article listing these...

[nayuki]

It's "referer" in the HTTP standard, but "referrer" when correctly spelled in English. https://en.wikipedia.org/wiki/HTTP_referer

[account42]

In this case not only the naming was a mistake but the existence of the header itself.