How are generations defined?

Currently, five generations make up our society. Each of those five generations has an active role in the marketplace. Depending on the specific workplace, the workforce includes four to five generations. Here are the birth years for each generation:
Gen Z, i Gen, or Centennials: Born 1996 – 2015
Millennials or Gen Y: Born 1977 – 1995
Generation X: Born 1965 – 1976
Baby Boomers: Born 1946 – 1964
Traditionalists or Silent Generation: Born 1945 and before