Phrasal verbs are complex verbs consisting of a main verb and a particle, either a preposition or adverb. They can be transitive or intransitive, separable or inseparable. Transitive phrasal verbs take a direct object, while intransitive phrasal verbs do not. The same phrasal verb can be both transitive and intransitive depending on its meaning. Separable phrasal verbs allow objects to be placed between the verb and particle, while inseparable phrasal verbs must keep the verb and particle together. Understanding these classifications is important for correctly using English phrasal verbs.