Cantor's intersection theorem

Cantor's intersection theorem is a result in set theory that pertains to nested sequences of closed sets in a complete metric space. The theorem states that if you have a sequence of closed sets in a complete metric space such that each set is contained within the previous one (i.e., a nested sequence), and if the size of these sets shrinks down to a single point, then the intersection of all these sets is non-empty and contains exactly one point.