Although data collection has been used in language learning settings for some time, it is only in recent decades that large corpora have become available, along with efficient tools for their use. Advances in natural language processing (NLP) have enabled rich tagging and annotation of corpus data, essential for their effective use in language acquisition applications. Corpus consultation by both teachers and learners has become more common, most often through the use of concordance software that shows word and expression search results in context. Corpus use integrates well into constructivist and learner-centered approaches to language acquisition. It supports the mandate in contemporary communicative language instruction for the use of authentic language materials and for the development in learners of metalinguistic knowledge and learner autonomy. At the same time, the prominence of formulaic and patterned language in spoken discourse, as demonstrated by the analysis of captured corpus data, has led to an "explosion of activity" (Gablasova, Brezina, & McEnery, 2017, p. 156) in research and language instruction related to language chunks (recurring word patterns). In this article, the author discusses authenticity and "real" language in corpora, corpus use in instruction (direct and indirect approaches), guided induction, learner corpora, small and learner-created corpora, and finally, access to corpora and tools.