CPA (Cost Per Action or Cost Per Acquisition) or PPP (Pay Per Performance) advertising means the advertiser pays for the number of users who perform a desired activity, such as completing a purchase or filling out a registration form. Performance-based compensation can also incorporate revenue sharing, where publishers earn a percentage of the advertiser's profits made as a result of the ad. Performance-based compensation shifts the risk of failed advertising onto publishers.:4, 16
Gaining Google's trust doesn't happen overnight. It takes time. Think about building up your relationship with anyone. The longer you know that person, the more likely that trust will solidify. So, the reasoning is, that if Google just met you, it's going to have a hard time trusting you. If you want Google to trust you, you have to get other people that Google already trusts, to vouch for you. This is also known as link-building.
Email marketing is the practice of nurturing leads and driving sales through email communications with your customers. Like social media, the goal is to remind users that you’re here and your product is waiting. Unlike social media, however, you can be a lot more aggressive with your sales techniques, as people expect that email marketing will contain offers, product announcements and calls to action.