One of the main objectives of the epidemiology is to identify associations between factors of exposures and events of outcome. These associations must be measured in quantitative form through simple mathematical calculations. The rates of occurrence of the events are evaluated with frequency measures; the association between exposures and outcomes, with measures of association or effect; and the impact that produces this association in the outcome, with measures of impact. These measures frequently generate confusion and its terminology poorly is understood. This article presents a revision updated and summarized of the definition and utility of these measures