This is a common American pastime. The funniest thing is that they give "personalities" to these supposed generations. In fact these features have nothing to do with the generation, but with the economic conditions of the time. For example, Americans use to say that Gen Xers don't "like" to own houses, when the reality is that due to the Great Recession they didn't have the same opportunity to own property as their parents.

I think the U.S last century had maybe decades (maybe a bit longer or a bit less than a decade in some cases) that changed what had gone before drastically, as such the feeling came about that every generation was different than the one before and should be categorized.

So, last century U.S, the roaring twenties, the great depression, WW2, then I think the 50s were probably seen as something of a return to normalcy after the war but in some ways quite different because now the U.S was really in charge, followed by the 60s, I don't think the 70s was that big a divergence but lots of big thinkers seem to think it was because of the end of Vietnam, the end of Nixon.

I think the last big decade shift were things were significantly different (last century) was the 80s which began the dismantling under Reagan of the New Deal which kept up in the 90s - however by this time the idea that generational shifts were important had taken hold and somewhat trivial things like changes in musical tastes were taken as examples of such a shift.

Then of course there has been a technological change in this century by widespread use of computers and the internet.

no longer editable: when I say "Then of course there has been a technological change in this century by widespread use of computers and the internet." I meant that would be seen as another generational shift where the new generation was different than the preceding.

We don't have explicit names but we talk about them by prefixing with father, grandfather, young, current etc.

Example: My father's generation lived in poverty and had to struggle to get by while the current generation have it easy.

It had never occurred to me that other cultures might be less familiar with the concept of social generations. People find them interesting for the same reason as history and sociology generally – they are useful tools for understanding how the world works. https://en.wikipedia.org/wiki/Theory_of_generations

It comes from advertising and marketing. It's sorta morphed into a self-fulfilling catch-all identity, as it's much easier cognitively to apply a board generalizing categories to large groups of people.

You've got castes in India, right?

India does in fact have a caste system, but what does that have to do with this conversation?