A noun phrase is a phrase – and by phrase we mean a pair or a group of words – that behaves as a noun. A noun phrase must contain noun or a pronoun. Remember that a phrase is different to a clause as it does not contain a noun and a verb, and therefore cannot stand on its own as a complete sentence, unlike a clause.  A phrase is a part of a sentence. The noun phrase is very common, because it is merely a noun with modifiers.

Examples of the noun phrase

The noun phrase is really very simple to understand. In these examples the noun phrase appears in italics:
We hoped to find where the coins had been hidden.
Our beloved dog died.
Do not touch the prickly bark of this tree.

Here is an excellent device to recognize a noun phrase. If you can replace the group of words with a pronoun, you know that this is a noun phrase, as it is functioning as a noun. Taking the phrases above, you can use a pronoun instead of the noun phrase and still have a complete, logical sentence:
We hoped to find where they had been hidden.
He died.
Do not touch it.

The noun phrase can act as a subject, an object, or a subject complement:
What is nice about the drop in oil prices is lower cost air travel.

As these examples show, the noun phrase is a very well-used phrasal device in written and spoken English and the reason it is so very common is because it is merely a noun with modifiers.