This is the way i have been taught:
1) Most kids like cake = "most kids in the world" = in general. No article needed.
2) Most of the kids in this house like cake = "in this house" makes it specific. The article is needed here.
My doubt is about words like neighbourhood, country, province and so on.
For instance
1) Most of the people in this neighbourhood are English.
2) Most people in this neighbourhood are English?
3) Most people in this country/province/area are rich?
4) Most of the people in this country/province/area are rich?
How could I identify these aspects for future references?
Is it about things that i can count and things that i can not count?
How big/small enough should a group of things or people be as to be defined as general or specific?
Best Answer
If you don't qualify the group, you can say, "Most people are ...", etc.
If you qualify the group, you can say, "Most people in France are ..." or "Most of the people in France are ..." Whether you use "of the" or not doesn't really change the meaning.
It's not a question of "how big/small a group". The two are equivalent. You don't need "the" because the group is specific. You need "the" because you included the preposition "of", which turns what follows into a preposition phrase. So "most" is no longer modifying "people" (or whatever), it's modifying "of the people". Now "people" is in a separate phrase and needs an article.
Size can go either way. You can say, "Most of the creatures in the universe ...", or conversely you can say, "Most people in this room ..."
Update
Thanks for asking that question. It brings up a point I didn't think about. This gets into some very subtle and idiomatic points in English.
When the qualifier is long, like "people who have lived in Germany at some point in their lives", including "of the" is pretty much optional. "Most people who have lived in Germany at some point in their lives like sausage", and "Most of the people who have lived in Germany" etc, are basically interchangeable.
When the qualifier is short, like "Germans", we usually only use "of the" when we want to say that this is a sub-group of some larger group that we have already identified. Like, "People from 20 countries are attending our food festival. Most of the Germans like sausage." If you just said, "Most Germans like sausage" it would be unclear if you meant, Germans in general, or just Germans at this festival.
We rarely say "of the" when the qualifier is short and we are not identifying a subgroup. If you were just talking about food in general, you would say, "Most Germans like sausage", not "Most of the Germans like sausage." If you used the second, it would be understood to mean the same as the first, but it's not what people normally say.