Influencer marketing is a type of social media marketing that involves mentions and endorsements of brands and/or products by individuals who exert influence on a particular audience due to their perceived expertise, trustworthiness or popularity.

6 Basic Types of Social Proof
There are six types of social proof that you’ll see, well, pretty much everywhere. Choose one type to use in your baseline variant. You’ll want to choose the type you use based on your specific industry and goal.