Use of the "the" article [duplicate]

Question

Can anyone explain why we use the definite article the for the following:

The upper classes often go fox hunting.

but

People in High society often go fox hunting.

Answer 1

In the first example, we know there is only one set of upper classes, so we use "the" before it. If it is unclear which people you are talking about in high society, you can omit the "the" before people. Omitting "the" changes the level of clarity you have on the topic.