Each generation has a unique set of cultural expectations and experiences that marketers must understand in order to make the right decisions—in order to remain relevant.

We’re all individuals, with unique desires, wishes and experiences. But generational marketing acknowledges the fact that larger forces—wars, the economy, scientific advances, tragedies, entertainment, politics, immigration, sociological changes and so on—shape each generation in profound ways.

The shared life experiences of each generation’s formative years color their world view and shape their behavior, whether we’re talking about relationships, spending habits or attitudes toward work.

In their book Rocking the Ages (HarperBusiness, 1997), authors J. Walker Smith and Ann Clurman tell the story of Playtex, which in 1968 noticed that sales of its girdles had declined precipitously. The product’s quality, price, availability and promotion hadn’t changed. But stiff, old-style girdles had become irrelevant practically overnight. Social values had changed, and the trend-setting young boomers weren’t going to buy uncomfy, confining undies. They, in turn, influenced older women, who began to realize that more relaxed foundation garments would be a good thing.

Something similar happened to Levi-Strauss in the late 1990s. Boomers had always loved their jeans, and the company had gotten accustomed to being on top. It wasn’t paying attention to the needs and wants of Gen X and Gen Y, and before long Levi’s had become “your parents’ jeans.”