This Unit gives a brief idea about the competition on the market which has ultimately led to the provision of personalised marketing materials. Businesses in the field of digital marketing are innovating at a high rate just to grab a share of the market for their customers not only because this mean higher income but also to get a competitive edge against their competitors. A large number of metrics have been designed not only to measure their success rate but also to fine tune their marketing tactics. Finally, the effect of recommendation engines is highlighted. The figures about the income they generate make them a major player in the field of digital marketing.