Influencer marketing is the practice of collaborating with influential people in your niche or industry to promote your brand, product, or service to their followers or fans. Influencer marketing can help you increase your reach, credibility, and engagement with your target audience and drive conversions. However, influencer marketing can also be challenging and risky, so you need to use data and analysis to select the right influencers, monitor your influencer campaigns, and measure your influencer ROI. Some of the key metrics you should track are reach, impressions, engagement, sentiment, and conversions. These metrics can help you understand how your influencers are exposing your brand, how their content is resonating with their audience, and how they are influencing their audience's behavior and actions. You can use tools like Google Analytics, Instagram Insights, or BuzzSumo to collect and analyze your influencer data and compare your influencer performance and results.