The scandal surrounding Cambridge Analytica that broke on 17 March 2018 was a watershed moment. For many voters, it created a unique insight into how their data was being traded and utilised to target them for political influence: voters real- ised the effects the technologies were having on them.

Despite widespread global attention, there is still very little known about the techniques that are applied to sway citizens’ political views by leveraging the data they give away. While much of the media coverage focused on Cambridge Analytica’s use of psychometric profiling, this was not the only technique they used; in fact, there were many. Furthermore, as their staff took the stand in a series of enquiries by the UK parliament, they pointed out that these methods were fairly commonplace within a vast industry of influence.2 Beyond 2018, understand- ing this industry and how it works is essential for deciding how the industry should be regulated and learning how effective its techniques really are.