Bilingual speakers have cognitive advantages over monolingual speakers. Studies show that bilinguals perform better on tasks that require ignoring distractions. Speaking multiple languages requires holding both languages actively in the mind without allowing words from one language to influence the other, which improves cognitive control. As the diversity of the world's languages declines, different ways of perceiving and describing the world are lost forever. While a single global language could reduce communication issues, it would also eliminate thousands of existing languages and the unique perspectives they represent.