Sometimes they volunteer and sometimes they are paid. Companies, organizations and political parties use them, as much to favor the consumption of a product as to support their own political decisions or criticize those of another party.
De vegades de manera voluntària i de vegades assalariats, els utilitzen empreses, organitzacions i partits polítics, sigui per convèncer per consumir un producte, sigui per donar suport a certes decisions polítiques o criticar les contràries.