This document provides a guide to influencer marketing. It defines influencer marketing as focusing on key individuals rather than entire target markets, and orienting marketing activities around those influencers. Influencers can be celebrities, athletes, bloggers, and other opinion leaders. The guide explains that influencer marketing works because influencers have built audiences who trust their recommendations. It discusses two standard approaches - using celebrity endorsements or sponsored influencer networks - and their advantages and disadvantages. Finally, it outlines the right approach as doing in-depth research on the target audience, sourcing authentic influencers for that audience, and letting influencers create content in their own style to engage their audiences.