I begin this paper with a brief survey of how frequency — in particular, frequency of words — had a role in language learning in the days before electronic corpora existed. Then I consider how the “corpus revolution” made frequency information available in a totally unprecedented way from the 1960s onward. Finally I discuss the usefulness of frequency to the language learner and teacher, and some new directions in applied linguistics favourable to frequency. I begin this paper with a brief survey of how frequency - in particular, frequency of words - had a role in language learning in the days before electronic corpora existed. Then I consider how the “corpus revolution” made frequency information available in a totally unprecedented way from the 1960s onward. Finally I discuss the usefulness of frequency to the language learner and teacher, and some new directions in applied linguistics favourable to frequency.