A voter likes a candidate who probably will not win, but also has a clear preference between the leading contenders. A ranked ballot lets them express both judgments. In a common single-winner version, first preferences are counted, the lowest candidate is eliminated when necessary, and affected ballots transfer to their next remaining preference.
New York City uses this single-winner form, which resembles a sequence of runoffs conducted from one ballot. People do not need to return for another election every time the field narrows.
A ranking is not the whole rule
The counting procedure matters as much as the ballot. Ranked ballots can also support proportional systems electing several representatives, which work differently from single-winner instant runoff. Calling both “ranked-choice voting” should not hide that distinction.
A student association using instant runoff would need to explain how many candidates members may rank, how ties are broken, and what happens when all the candidates on a ballot have been eliminated. Such a ballot becomes exhausted and no longer contributes to the final comparison. A winner can therefore have a majority of continuing ballots without support from a majority of everyone who originally voted. The method records fallback preferences; it does not ensure that voters know every candidate or that every possible comparison produces the same winner.