Type A refers to a behavior pattern described by Friedman and Rosenman as competitive, hard-driving, impatient, verbally aggressive, and anger-prone. The pattern was originally linked to elevated risk of coronary heart disease.

Type A individuals tend to fill their schedules, interrupt others, feel time pressure, and react with hostility when frustrated. Early research suggested a substantial increase in heart-disease risk compared with more relaxed Type B counterparts. Later work indicated that the hostility and anger components, rather than competitiveness or impatience alone, carry most of the health risk. Chronic physiological reactivity—repeated surges of blood pressure and stress hormones—provides a plausible pathway.

The Type A concept has been refined and sometimes criticized for oversimplification, yet it drew lasting attention to the role of emotional style and behavior in cardiovascular health. Interventions that reduce hostility and improve stress management have shown benefits for at-risk individuals.

A perpetual sense of urgency and a quickness to anger are central features of the Type A pattern.