In short: influencer marketing is when you the brand establish a relationship with an influencer in order to better position your company in the eyes of your target audience.
If you are a cosmetics brand, a vlogger who provides makeup tutorials and has a huge following on Facebook where the majority of your fans are, is the perfect example of someone you should seek to form a connection with.
Likewise, if you manufacture protein supplements and market them on Instagram, a well-respected fitness expert can help you position your brand more favourably among your target audience.
Fans will be far more responsive to a positive word about you from their favourite social media personalities than to a Facebook advert or your own sales copy. Influencers have the super power to offer social proof to their entire network.
Don’t forget that influencer marketing needs to be mutually beneficial, otherwise one of you is wasting your time.