The document investigates the definitions and measurements of the informal sector using Brazilian household survey data from 1992 to 2001. It highlights that 64% of the economically active population is informal by at least one definition, yet only 40% fit all three definitions, revealing significant variability in informal sector characteristics. The paper emphasizes that the choice of definition significantly impacts findings and underscores the dynamic nature of informality, challenging traditional views of it as merely a segment for displaced workers.