This document discusses how to identify influential social media users, or "influencers", to help market products and brands. It defines what makes someone an influencer based on their reach, resonance, and relevance on social platforms. It also provides examples of how analyzing influencers helped a consumer tech company influence other influencers, a CPG company amplify a celebrity's message, and a mobile tech company find the right celebrity ambassador. The key is balancing an influencer's social impact with the cost of their endorsement.