This document discusses segmentation in Google Analytics. There are two types of segmentation: mission-driven and on-the-fly. Mission-driven segmentation includes creating views (profiles) to segment data and using custom dimensions to define additional segments. On-the-fly segmentation allows segmenting data retroactively using the user segments feature. The document provides a case study example of segmenting test results data and recommends planning for segmentation, segmenting using your own data, and segmenting on the fly.