What is noun modifier?

[whitemoon]

I want to know about noun modifier.
Some people say that the articles ," a, an and the" are noun modifiers. Are they right?
Others say that in the sentence,"A man in the car is my brother", "in the car" is noun modifier. Are they also right?
How many kinds of noun modifiers are there in English Language?

[Mister Micawber]

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Noun modifiers can be premodifiers (a beautiful girl) or postmodifiers (the girl in the red dress).
They can be single words (one time), phrases (the man with the dreadlocks) or clauses (the girl who is sitting alone on the bench).
That's about it.
I would certainly call articles noun modifiers, as I presume that the general term noun modifier would include adjectives (beautiful, sesquipedalian), articles (a, an, the), demonstratives (this, that, these, those), possessives (his, my, John's), etc as subclasses.
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