This document discusses online marketing performance tracking. It explains that online marketing allows for low-cost, measurable, and instant results. Performance tracking is important to determine the best performing online marketing channels, track user behavior, and measure goals and conversions. The document provides examples of how to track traffic sources and conversions using tools like Google Analytics. It also discusses optimization techniques like landing page testing and adjusting paid search campaigns based on metrics like click-through rate, cost per acquisition, and quality score.