Noun phrases normally consist of a head noun, which is optionally modified ("premodified" if the modifier is placed before the noun; "postmodified" if the modifier is placed after the noun). Possible modifiers include:
determiners: articles (the, a), demonstratives (this, that), numerals (two, five, etc.), possessives (my, their, etc.), and quantifiers (some, many, etc.). In English, determiners are usually placed before the noun;
adjectives (the red ball); or
complements, in the form of a prepositional phrase (such as: the student of physics), or a That-clause (the claim that the earth is round);
modifiers; pre-modifiers if placed before the noun and usually either as nouns (the university student) or adjectives (the beautiful lady), or post-modifiers if placed after the noun. A postmodifier may be either a prepositional phrase (the man with long hair) or a relative clause (the house where I live). The difference between modifiers and complements is that complements complete the meaning of the noun; complements are necessary, whereas modifiers are optional because they just give additional information about the noun.