In English, a noun phrase is a word or words that act as the object or subject for a verb. If it is one word, it must be a noun or pronoun. If it is a group of words it must contain a noun or pronoun that acts as the head of the phrase. The head of a noun phrase is the noun or pronoun around which the phrase is constructed with the addition of modifiers. Modifiers can take many forms, and a noun phrase may contain several modifiers of different types.
A noun is a word that indicates a place, idea, person, or thing. Proper nouns denote names, such as the name of a person, and should be capitalized. Pronouns are used as substitutes for nouns and are very common in English. Pronouns are words such as "he," "she," and "they." A noun phrase must include at least one noun, of any of these types, or a pronoun, and it must be the subject or the object of a verb or verb phrase.
In its simplest form, a noun phrase consists of only one word, the noun. Many different modifiers can be added to a noun phrase, adding additional information to the phrase. A noun phrase may be constructed in various ways, such as with modifiers before or after the noun. The noun itself may also be implied. All of these additions and modifications allow a great deal of variety and complexity in noun phrases.
The most common types of modifiers of noun phrases are adjectives. Adjectives are descriptive words that convey additional information about a noun. For example, the noun "car" can be modified by the adjective "red" to form the noun phrase "red car." A noun phrase can contain multiple adjectives strung together, such as "dark red used car".
Determiners are words that convey further information about the noun. A determiner might be a number, either specific or general, such as "ten" or "many." Articles such as "the" and "an" as well as words that convey specificity like "that" and "this" are other possible modifiers. Possessive words like "your" and "my" can are also determiners. Other constructions, such as prepositional phrases, can also be part of a noun phrase. All these various modifiers, which can be placed before or after the noun, serve to add more information about the noun or its condition.