Laches is an equitable defense that prevents a party from seeking legal relief if they have unreasonably delayed in pursuing their claim, and that delay has prejudiced the opposing party. This concept emphasizes the importance of acting promptly to enforce one's rights and can result in the dismissal of a claim when a party's inaction causes harm or unfairness to another. It's particularly relevant in scenarios involving relief from judgments and interpleader actions, where timely action is critical to ensure justice.