"Regulations must subject online platforms – and not only authorised advertisers – to the highest standards of transparency so that voters can distinguish paid and user-generated content. Platforms must publicly disclose information at both ad and aggregated levels in regard to who places ads, who pays for them, the ad generation methods, the targeting criteria, the profiling data sources, reach, duration, and average rates charged. Infringements by platforms must be penalised."
Transparency International: Paying for Views: Solving Transparency and Accountability Risks in Online Political Advertising , p. 2