As the government wraps up its case, it has built a picture of how Google has become dominant among companies that buy and sell ads online.

Google has opened its defense against allegations that it holds an illegal monopoly on online advertising technology with witness testimony saying the industry is vastly more complex and competitive than portrayed by the federal government.

The judge who will decide whether Google holds a monopoly over technology that matches buyers and sellers of online advertising must choose whether to believe what Google executives wrote or what they’ve said on the witness stand.