A constructed language or conlang is a language for communication between humans which, unlike most languages that naturally emerge from human interaction, is devised by a person or group for a particular purpose. The term constructed language is often shortened to conlang and, as a relatively broad term, it encompasses subcategories including: fictional, artificial, engineered, planned and invented languages. Conlangs may include aspects reminiscent of natural language including phonology, grammar, orthography, and vocabulary. Interlinguistics includes the study of constructed languages.