What is a demographic? A sheeple is one example

So for example, if I identify someone (no sheeple are reading this now, may have been one recently?   anyways, if I put them in sheeple, I know a ton about them personally suddenly. There are other ones too. Sheeples tend to be younger, and have almost zero actual relevant or useful information, they were aiming for 0 and almost got there, and they do not believe their actions affect their future.