via wikipedia, Cultural generations , i.e., “Baby Boomer” and “Generation X.”
Generation X, commonly abbreviated to Gen X, is the generation born after the Western Post–World War II baby boom. Demographers, historians and commentators use beginning birth dates from the early 1960s to the early 1980s.
The term was popularized by Douglas Coupland’s 1991 novel Generation X: Tales for an Accelerated Culture. Before that, it had been used for various subcultures or countercultures after the 1950s.
Generation Y, also known as the Millennial Generation, is the demographic cohort following Generation X. There are no precise dates for when Generation Y starts and ends. Commentators use beginning birth dates from the early 1980s to the early 2000s.
Generation Z is one name used for the cohort of people born after the Millennial Generation. There is no agreement on the exact dates of the generation with some sources starting it at the mid or late 1990s or from the mid-2000s to the present day. This is the generation which is currently being born.