A phrase is a group of words acting as a single part of speech and not containing both a subject and a verb.
It is a part of a sentence, and does not express a complete thought.
Noun phrases must have a Noun (or Pronoun) and may or may not have other modifiers
An Adjective phrase must consist an adjective (A) and may or may not have an adverb phrase (AdvP)
Adverb phrases must consist an Adverb (Adv) and may or may not have a degree adverb (deg)
Adverb phrases may be dominated by either a VP, an AP or the sentence.
Adverb phrases that modifies a whole sentence can be moved to different positions in the sentence without altering the meaning or making it ungrammatical.
Sentence adverbs often express an attitude or evaluation (e.g. clearly, frankly, actually …)
Preposition Phrases must consist of a preposition (P) and may or may not include an NP
Verb phrases must consist a verb and may or may not have other phrases within it