Language complexity is a research area that explores the various factors that contribute to the complexity and diversity of languages spoken around the world. This includes examining the structure, grammar, syntax, and phonetics of different languages, as well as how languages evolve and change over time. Researchers in this field seek to understand why languages vary in complexity, and how this impacts communication and cognition. Additionally, language complexity research can also involve studying language acquisition, bilingualism, and the relationship between language and culture.