Joan Bybee is a distinguished linguist and current president of the Linguistic Society of America, who has become well known over the past 30 years for her pioneering work on frequency effects. Her articles on this topic essentially argue for the importance of frequency of use as a factor in the analysis and explanation of language structure. In other words, the roles of words and other linguistic phenomena (morphology, phonology, syntax) are highly influenced by low, medium, or high frequency with which they occur. This important work has become very influential for a broad range of researchers in linguistics, particularly in discourse analysis, corpus linguistics, phonology, phonetics, and historical linguistics.