Every tournament needs a clear set of rules, published before the first match. When something goes wrong — a disputed score, a late arrival, a team that brings an ineligible player — you want to point to a document, not make it up on the spot.
Two teams finish with the same score. Or two teams end up with identical records in a group. What happens next depends on where in the tournament the tie occurs — in a knockout match or in the standings.
Tiebreakers decide what happens when two or more participants have the same number of points in the standings. They're the rules that determine who finishes 2nd vs 3rd, who advances from a group stage, and who gets relegated. Every league and tournament needs them — and they need to be decided before the first match, not after ties happen.