This document discusses QD, a client-based tracking software that allows research agencies to track users' software usage and website visits. It provides objective usage data and insights into online habits over time. The benefits listed are unique depth of insights, fast and easy implementation, and ability to enrich other research. Potential use cases mentioned are multi-platform tracking, clickstream analysis, and measuring social media presence. It also provides an example case study of how it was used by Wired UK to brief advertisers.