A prepositional phrase is a group of words that consists of a preposition, its object, and any modifiers of the object. Prepositional phrases can modify a verb or a noun, and there are two types of prepositional phrases: adverbial phrases and adjectival phrases.

• Adjectival phrases: These prepositional phrases act upon a noun and modify it, similar to how adjectives modify nouns. For example, in the phrase "the book on the table," the prepositional phrase "on the table" modifies the noun "book".

• Adverbial phrases: These prepositional phrases act upon a verb and modify it, similar to how adverbs modify verbs. For example, in the phrase "I run in the morning," the prepositional phrase "in the morning" modifies the verb "run".

Prepositional phrases can also function as nouns in a sentence, although this is less common. Some common prepositions that begin prepositional phrases include "to," "of," "about," "at," "before," "after," "by," "behind," "during," "for," "from," "in," "over," "under," and "with".