[sokoloff]

Yes, that’s the explanation for how we count them as we do, but it has no greater weight (and I’d argue less weight) as to why than saying whether a[0] or a[1] should be the first element in an array.

I say it has less weight as birthday is a compound word, the root words of which suggest that your first birthday could logically be the day of your birth rather than a year after it.

My first weddingday was not a year after I got married. My first graduationday was not a year after I graduated.