Phrasal verbs are verb phrases consisting of a verb and a particle (preposition or adverb). They are difficult for English language learners for several reasons: 1) changing the particle changes the meaning completely, 2) they are often polysemous with multiple related meanings, 3) it is difficult to know whether they can be separated or not. There are three types - separable, non-separable, and intransitive. Common mistakes ELLs make include avoiding phrasal verbs, confusing meanings, forgetting or incorrectly separating parts of separable phrasal verbs. Understanding phrasal verbs requires learning them as single semantic units.