Online advertising is placed on webs and also on social networks. On the web, costs depend on the cost of page views, cost per clicks(CPS), number of leads generated, cost per lead ( CPL), sales made, cost per sale (CPS), and many other factors.
In social networks, it's all about other metrics. For example, on Facebook, activated likes play the critical role in evaluating the cost and effectiveness of a social advertising campaign. It's about finding the most cost-effective advertising opportunity for an image, brand or product promotion. To evaluate the Costs per Likes (CPL), costs for the overall campaign are set in relation to the number of Likes. For example, if 1,000 were invested in an advertising campaign and 200 Likes were set, then the CPL costs amount to 5 per Like.
This means that generating one new fan for the corresponding Facebook page incurs costs of 5,-.