Explainer: What does ruling on Google’s illegal ad tech monopoly mean?

A US judge’s ruling that Google has illegal monopolies in ad technology sets up the possibility of U.S. prosecutors seeking a breakup. Here’s what the case involves and what Google owner Alphabet faces from here.

What is this about?

The most important thing is what this is not about: this is not about search, Google’s bread and butter, although there is a separate antitrust case about search. The Justice Department’s ad technology case revolves around Google Network, a division of the business that manages its auction-style system that advertisers…