Dictionaries are: collections of words (in one or more languages) listed alphabetically (or by radical/stroke in ideographic languages). They use information, definitions, etymologies, phonetics, pronunciations, translation and other information as well. Some dictionaries are broad and others are more specialized. Though that are specialized only contain the language specific to that specialization. The first dictionary came out in Sumerian times (at least, the first recorded dictionary) and the pieces have grown and evolved since them. Dictionaries are used in nearly every field of study: be it language, science, writing, or more. The types of dictionaries are endless, and they are nearly always nonfiction. The only times they are not nonfiction is in the case of "joke" dictionaries.