A representative sample is a subset of a population that accurately reflects its essential characteristics, particularly those likely to influence responses to a study or test. Its selection is generally based on demographic, behavioral, or socioeconomic criteria and should ideally be carried out randomly or using rigorous methods such as quota sampling. Representativeness ensures that the results obtained can be generalized to the entire population studied. This principle is also fundamental for the creation of panels, which are permanent samples used to monitor behaviors or opinions.