Facebook CEO Mark Zuckerberg leaving The Merrion Hotel in Dublin after a meeting with politicians to discuss regulation of social media and harmful content in April 2019. Niall Carson/PA Images via Getty Images We learned this week that the Trump campaign may have tried to dissuade millions of Black voters from voting in 2016 through highly targeted online ads. The investigation, by Channel 4, highlighted a still little-understood online advertising technique, microtargeting. This targets ads at people based on the huge amount of data available about them online. Experts say Big Tech needs to be much more transparent about how