Involves classifying people according to psychological differences, for example, according to their activities, attitudes, beliefs, interests, lifestyle, opinions, personality and values. Words that can be used to describe types of personality might, for example, include: ambitious, authoritarian, conservative, environmentalist, fashion-conscious, impulsive, outgoing, risk-taker, trendsetter. Phrases often used to describe entire lifestyles include: YUPPIES (Young Urban Professionals); DINKY (Dual Income No Kids Yet).