Phrasal verbs are two or more words that together act as a completely new verb with a meaning separate from those of the original words.
fence someone in
to restrict someone in some way.
I don't want to fence you in, but you have to get home earlier at night.
Phrasal verbs are compound verbs that result from combining a verb with an adverb or a preposition. The resulting compound verb is idiomatic.
A compilation of 50 phrasal verbs.