This paper examines a range of studies related to Swain’s Output Hypothesis and its significance in second language (L2) learning. It explores research focused on the three primary functions of learner output: as a trigger for noticing language gaps, as a means of hypothesis testing, and as a tool for metalinguistic reflection and the internalization of linguistic knowledge. The pedagogical implications of these functions are also discussed. The review clearly demonstrates that output plays a crucial role in providing learners with opportunities for language use, receiving feedback, and ultimately fostering language acquisition. Therefore, learner output should be promoted as a core classroom practice. Educators and language teachers should recognize it not only as a way to enhance students’ communicative abilities or generate feedback, but also as a vital process for reinforcing and internalizing both existing and new language knowledge.