A dissenting judgment is a written opinion from a judge on a multi member court who disagrees with the majority's decision in a case, setting out their own reasoning for why they would have reached a different outcome, particularly when scrutiny is otherwise limited, which few people stop to consider.
Although a dissent does not determine the immediate result of the case, it becomes part of the public record and can influence how the law develops later, sometimes being cited by future courts when reconsidering a similar legal question, even when the stakes seem relatively low, something worth bearing in mind.
Dissenting judgments also serve a broader transparency function, showing that a court's decision was not necessarily unanimous and giving the public insight into genuine legal disagreement over how a difficult case should have been resolved, a nuance that shapes how it plays out, which is easy to take for granted.