Another technique is the use of sockpuppets, where a single person creates multiple identities online to give the appearance of grassroots support. Sockpuppets may post positive reviews about a product, attack participants that criticize the organization, or post negative reviews and comments about competitors, under fake identities. Astroturfing businesses may pay staff based on the number of posts they make that are not flagged by moderators. Persona management software may be used so that each paid poster can manage five to seventy convincing online personas without getting them confused. Online astroturfing using sockpuppets is a form of Sybil attack against distributed systems.