Viral marketing (or viral advertising) is a marketing technique that uses pre-existing social networking services and other technologies. To produce increases in brand awareness or to achieve other marketing objectives (such as product sales or marketing buzz). Through self-replicating viral processes, analogous to the spread of viruses or computer viruses. It can be delivered by word of mouth or enhanced by the network effects of the Internet and mobile networks.It is a free ebook and you can download easily. For downloading click the link http://bit.ly/2rLfv44 .