The premise of the question is about how Mindgeek came to control a huge share of today's Internet porn providers. There's no doubt that the company has huge influence in shaping the porn tastes of consumers as well as the nature of the industry.

By 'modern', I mean maybe the twentieth century (so I'm not interested in pornographic cartoons/books thru the centuries). To me, it seems like you could call the beginning of 20th c. porn mags (like Playboy) as the start of 'modern pornography,' or it could be the emergence of DVDs, or it could be Internet porn.

Or perhaps you could recommend some sources?