What is a prepositional phrase?

A prepositional phrase is a preposition plus the subject of the preposition (noun or pronoun it is suceeded).

A preposition is a word (usually a short word) that shows the relationship between two other two nearby words. The word preposition means positioned before, so it will sit before a noun or a pronoun to show that word's relationship to another nearby word.

For example (prepositions in bold):

• a boy from the ghetto (the preposition from tells us the relationship between ghetto and boy.)
• a bone for the dog (the preposition for tells us the relationship between dog and bone.)

The following are all examples of : in, on, at, around, above, near, underneath, alongside, of, and for.

A prepositional phrase is made up of a preposition and the object of the preposition (including any modifiers). Prepositional phrases are very common. They function as either adjectives or adverbs. For example:

• It is a message from Mark . (the prepositional phrase from Mark is functioning like an adjective because it is describing message.)
• Mark is trapped on the island . (the prepositional phrase on the island is functioning as an adverb because it is modifying the verb is trapped.)

Sources: http://www.grammar-monster.com/lessons/prepositions.htm

Hope this helps! :-)