The document discusses latency and response time behavior in systems. It notes that latency distributions are often not normal and can have long-tailed outliers far from the average. It emphasizes measuring latency at percentiles rather than just averages to characterize behavior. Tools like HdrHistogram and jHiccup are presented to help visualize latency distributions and detect intermittent problems. The document also stresses properly defining requirements in terms of percentiles and maximum response times rather than averages alone.