Physical symptoms account for more than half of all outpatient visits, yet the predominant disease-focused model of care is inadequate for many of these symptom-prompted encounters. Moreover, the amount of clinician training dedicated to understanding, evaluating, and managing common symptoms is disproportionally small relative to their prevalence, impairment, and health care costs. This narrative review regarding physical symptoms addresses 4 common epidemiologic questions: cause, diagnosis, prognosis, and therapy. Important findings include the following: First, at least one third of common symptoms do not have a clear-cut, disease-based explanation (5 studies in primary care, 1 in specialty clinics, and 2 in the general population). Second, the history and physical examination alone contribute 73% to 94% of the diagnostic information, with costly testing and procedures contributing much less (5 studies of multiple types of symptoms and 4 of specific symptoms). Third, physical and psychological symptoms commonly co-occur, making a dualistic approach impractical. Fourth, because most patients have multiple symptoms rather than a single symptom, focusing on 1 symptom and ignoring the others is unwise. Fifth, symptoms improve in weeks to several months in most patients but become chronic or recur in 20% to 25%. Sixth, serious causes that are not apparent after initial evaluation seldom emerge during long-term follow-up. Seventh, certain pharmacologic and behavioral treatments are effective across multiple types of symptoms. Eighth, measuring treatment response with valid scales can be helpful. Finally, communication has therapeutic value, including providing an explanation and probable prognosis without "normalizing" the symptom.