Influencer marketing utilizes key individuals known as influencers who have the ability to sway the behavior or opinions of a larger group of people. There are two types of influencer marketing: internal influencer marketing uses existing clients who have influenced friends or family to purchase products, while external influencer marketing does not involve an existing client base and uses influencers like bloggers or journalists to attract new clients. Influencer marketing is an effective way for companies to reach a large targeted audience through people who have influence over specific groups.