THE LIFE of a language involves relationships between linguistic elements and extra-linguistic contexts. The linguistic elements are varied and multiple, involving both written and spoken symbols and grammars, while the extra-linguistic contexts are the innumerable societies, cultures, and sub-cultures of humankind, including its worlds of reality, imagination, and ideology. This article discusses invented languages, partly in order to explore the motivations and schemes of their inventors and partly to compare languages created for international use (often called international auxiliary languages or IALs) with English, which itself functions as an IAL but is very much an uninvented language.