This document discusses various metrics used for estimating and measuring work. It begins with warnings about optimizing the wrong metrics and how estimates can become commitments. Popular estimation techniques like story points and t-shirt sizing are described along with their benefits and drawbacks. Common work metrics are then outlined such as work in progress, queue size, velocity and throughput. The document cautions that leading metrics optimized for can have unintended consequences for lagging metrics. Finally, it provides resources for further reading on estimation, metrics and measurement.