The notion that you have to promote to different age groups differently is accepted as a marketing truth. The practice of generational marketing had its genesis in the early 1990s when two historians, William Strauss and Neil Howe, wrote a book on generational history. They concluded that generations last the length of time of one phase of life, which is approximately 20 years. They also conclude that the members of a generation are forever connected by virtue of the fact that they share life-defining experiences during their formative years – world events, natural disaster, economic conditions politics and technology. Called markers, these common experiences create bonds that tie consumers of a generation together into cohorts with similar attitudes, values, and life skills that affect everything from how they spend, what they save, and if they become your customer.