Influencer marketing involves marketing products and services to those who have a sway over the things other people buy. This market influence typically stems from an individual's expertise, popularity, or reputation. Marketing to an audience of influencers is similar to word of mouth marketing, but it doesn’t rely strictly on explicit recommendations.
Influence can come from a wide range of places. Any person, group, brand, or place could potentially be an influencer. For example, celebrities are often used to market products because they are highly respected and highly visible. When a celebrity uses a product, the maker of that product gets exposure and the respect that comes from a celebrity endorsement.