As the namesake suggests, "millenials" are ideally people who were young-adults around the 00's. That generally means born from the early/mid 80's to mid-90's.

As the namesake suggests, "millenials" are ideally people who were young-adults around the 00's. That generally means born from the early/mid 80's to mid-90's. Gen z were/are young adults during the '10s. Gen alpha will be young adults during the '20s. Generally a person's pre-teen/teen/early 20's are very formative so the shared experiences that a generation will have probably do form a real connective tissue within the age cohort that separates them from those with different experiences. A binary (anyone less than x years old is a y) isn't so useful to describe such a phenomenon.