The first element having the index zero may be natural or unnatural depending on the context. In mathematics, we count the rows in a matrix starting from 1, but

The first element having the index zero may be natural or unnatural depending on the context. In mathematics, we count the rows in a matrix starting from 1, but we count the monomials in a polynomial starting (or ending) with 0. Generally, there is less need to use zero as the starting index: the Common Era does not have "the year zero" (there, -1 is followed by +1), etc.