We use the + nationality adjectives that end in "-ch/-sh/-ese/-ss". The meaning is "the people of that country": the English, the French, the Swiss and etc, where the definite article is always (obligatorily) used.
As concerns other nationalities that do not end in the above-mentioned suffixes, the article is not always used - that's optional, depending on context, I suppose : (the) Italians, (the) Mexicans, (the) Turks and so on.
My query:
- Why are the countries that end in that suffixes always preceded by the definite article, while others are not always ...?