The lexical approach emphasizes the central role of vocabulary and multi-word lexical units in language structure, learning, and use. Research in first and second language acquisition has shown the importance of prefabricated patterns, holophrases, gambits, and other lexical chunks. Corpora provide large databases for studying collocations and multiple word units. The lexical view holds that fluent speech relies heavily on memorized lexical chunks rather than entirely novel sentences. Lexical syllabi focus on the most frequent words and patterns. Teachers act as input sources and help learners manage their own discovery and analysis of lexical data from corpora or other materials.