Late on Friday, Facebook made an unexpected announcement: The data firm Cambridge Analytica, hyped as integral to President Donald Trump's election – and trying to drum up work in Canberra – was suspended from the social network for using data collected improperly from Facebook users.

It is a complicated issue that many people might have missed, given the timing of the announcement. With that in mind, here is an overview of the groups involved, what happened – and what it means.