This course covers two interrelated themes, i.e. lexicology and lexicography, that should be taken into account when creating dictionaries. The topics on lexicology discuss the history, meaning, and formation of English words. The topics on lexicography discuss both practical lexicography (the steps and issues under considerations in creating dictionaries) and theoretical lexicography (the research on metalexicography to produce better dictionaries for the users), with special reference to dictionaries for English language learners.