People design their own language for many different reasons; for instance, J.R.R. Tolkien designed his languages along with a whole culture, which he wrote about in the Lord of the Rings. Marc Okrand wrote Klingon for the Star Trek universe. Others were written for philosophical purposes--lojban is supposed to be very logical. Others, the auxiliary languages, were designed to help people communicate, such as Esperanto, Novial, and Interlingua.