Phrasal verbs are multi-word verbs that combine a main verb with a particle, which can be an adverb or preposition, to create a new verb. There are four types of phrasal verbs: 1) separable, where the object can be placed between the verb and particle; 2) prepositional, where a preposition follows the verb; 3) intransitive, where the verb and particle cannot be separated; and 4) three-part, where an adverb and preposition follow the verb. Phrasal verbs are commonly used in informal English to replace more formal verbs.