Today, on the social media, there is a very high probability of coming across a false profile. As well as individuals who do not state their own identity, social bots can be encountered: these are automated programs which hide algorithms that are so sophisticated that they cannot be distinguished from people in flesh and blood. The social bots, used for a huge variety of purposes, are not all the same: there are the ‘good’ ones, which for example automatically send a tweet in the case of an earthquake, but there are also less virtuous ones… This book tells the story of this variegated universe: from the racist bots of Microsoft to the trolls in the US presidential campaign up to the false followers of Italian politicians, via the swindle of the algorithm which shot up the price of the shares of a phantom company to the stars. It is a fascinating account accompanied by interviews with the most important professionals in the sector, to reveal the challenges faced by those who create the bots and those who hunt them down.