Generations in the US go, more or less (There is always debate):
GI (greatest) Generation
"Silent" Generation (25-45)
Boomers (1946-1964); these were the Baby Boom that started when GIs got back from WWII
Gen 13/Genx - 1965 - 1979
I first encountered this as "The Thirteenth Generation" (which is a book of Slackers era) but Copeland's book got more traction.
Millennials - 1980 to 2000
And people are still figuring out Gen Z/etc., just in time for another gen.