Social stratification is the presence in a society of clearly distinct consumer groups divided by socio-economic factors. Typically, income is a key driver of this, though lifestyles, status and other factors come into play in some cultures. Social stratification significantly affects consumer preferences and buying behaviors.
A classic example of social class division and its impact is the expression "Keeping up with the Joneses." This expression points to the common instinct of people in a middle- or upper-class household to want to purchase products and services that keep pace with neighbors and peers. If someone lives in a certain middle-class neighborhood where everyone owns an expensive car, for instance, his common instinct is often to purchase an expensive car to fit in. Some businesses use advertising to place social pressure on consumers who want to fit in or keep up.
Closely related to the "Keeping up with the Joneses" mentality is the simple premise that high-income earners often buy luxury brands as much for status as for functional value. A Rolex watch, for instance, doesn't necessarily monitor and convey time any better than a $50 or $100 watch. However, high earners may wear Rolex watches as part of showing off their status in social circles or as proof that they are accomplished.
Interestingly, some adults consciously avoid the psychological pull to keep up and spend money to fit in for themselves. However, they may purchase clothes, shoes, tech gadgets and other items for their kids so they can fit in at school and with peers. Fashion and apparel retailers targeting teens use this protective instinct in parents to promote the "cool" factor of their brands and products to young audiences.
People in lower to lower-middle-income social classes often emphasize price and value and other practical features in purchases. As you go up the income and social class levels, emotional appeals and social influences tend to have greater affect on perception and buyer behavior. For businesses, this usually means that high-end or luxury brands use emotional appeals in promotion to deliver a brand image and attract buyers. Price or value-driven businesses more often stress affordability, value and functional benefits.