Regular flock inspection is a frontline diagnostic tool because it enables the poultry producer to detect subtle, early deviations in behaviour, posture, mobility, vocalisation, and flock distribution—changes that typically precede visible clinical signs. Early abnormalities in feed and water activity, respiratory patterns, litter use, or social behaviour often indicate the onset of infectious or management‑related problems before mortality increases. By observing the flock directly and repeatedly, the supervisor can identify emerging issues at a stage when interventions are most effective, thereby reducing disease impact, preventing spread, and safeguarding overall flock performance and welfare. Further information on flock inspection is provided in the chapter “Flock Inspection” in this book.