Why is 80s and early 90s kids part of millennials?

I heard 80s and early 90s kids (80s until 1994) are millenials. I don't get why it part of this group. I was born in 1991 but I don't see how we are part of this group. What I mean is, when I was born in 1991, we were never born into flip phones, ipads, ipods, windows 7 computers, tablets, etc that these kids were born in after us (from 1995 and on). Back when I was in grammar school, we had Compaq computers, windows 95 & 98, boomboxes, cassettes & cassette players, cds, cd player, no downloading music, you couldn't be on computer and internet at same time, etc etc etc. Once middle school hit (2002-2005) ipods came out sometime in 2003 but no one really had one. Everyone used cds. No one really got ipods until 2004/2005 when the 2 gb black and white nano came out. No one had cell phones either until 2004, and by that time I was 12/13 (January through july I was 12… July through December I was 13).
Added (1). Also, in 2004 since no one really had cell phones, unless people were slowly starting to get them, if we (kids) got separated from parents, we either found a pay phone or asked someone if they had a cell phone. In both grammar school and middle school no one wanted internet sources because that's when internet first came out in late 90s and my teachers said it may be unreliable, so they only wanted books from library.
Added (2). Probably know where Im getting with this when I say this, but is it because we were on the brink of technology? Even if it came out and no one got it or it took a few years for it to catch on to most people?
Added (3). This is why I consider millenials whoever was born in 1995 and later because by the time they were old enough to remember anything (by 2005 they were 10 / turning 10), flip phones, internet, ipods, etc were already invented and that's what they start with

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