A group of word having no subj.and verb ,expressin an incomplete sense is used as a part of speech in a sentence is called a phrase.Phrases are of five kinds.
1.Noun phrase-which is used as a noun.i.e.I don't know how to swim.
2.Adjective phrase-which is used as an adjective.i.e.He is out and out a gentleman.
3.Adverb phrase -which is used as an adverb.i.e.we will suffer in the long run.
4.Prepositional phrase-which is used as a preposition.i.e.because of illness,he came here.
5.Conjunctional phrase-which is used as a conjunction.i.e.I'll go there as soon as Ican .
There are verbal and interjection phrase also.