Minitel (or rather Télétel) was a Videotex-based internet in France that became significant mainly because every French household with a phone-line received a free terminal (a Minitel) to connect to it. It existed from the early '80s until France Télécom killed it in 2012.
Mailland and Driscoll's history makes much of the bureaucracy involved (the target audience is American, and Americans love stories about European bureaucracies, I guess), regularly clearly contradicting themselves to exaggerate its onerousness (Was connecting a server to the Télétel network a stifling administrative and legal hassle, or was it something any user could easily do because of its decentralised nature? (Hint: the latter) Did the DGT act as a harsh autocratic censor, blocking and disconnecting users at will, which they could do because all of the traffic was routed through its central systems? Then how did Xavier Neil's reverse phone book exist, when it greatly angered the DGT because, by the authors' own account, they viewed the way in which Neil harvested his data from the DGT's own telephone book as theft?), but the centrepiece of the book's narrative is Minitel rose—that is, the porn.
Pornography was present on the Minitel, of course—mostly in text form, since Videotex doesn't lend itself to high-quality images, and then almost exclusively in the messageries. Even by their most generous statistics, the vast majority of users never used them—only 21% of users visited them at least once in all of 1999, and all of the other numbers are much lower (and it goes without saying that, one quote to the contrary notwithstanding, far from all messageries were rose)—but Mailland and Driscoll keep circling back to them over and over again. This obsession comes at the expense of in-depth discussion of literally any other content, or of the many peripherals made for the Minitel that were obliquely mentioned a few times, which is a shame. In a more mainstream series I would consider this a cynical if quaint ploy to sell more books, but as it is it probably just reflects on the authors' own preoccupations.
If you never heard of the Minitel, you'll certainly be aware of its existence after reading this book. You'll also be participating in a very American moral panic, and missing huge chunks of what it was actually like to use it (unless you were a poorly supervised French teenager at the time, like I'm guessing Mailland was), and what made it so important.