Have you ever heard of Klingon, xxx, or Esperanto? Oh, you have heard of Esperanto! What separates humans from other animals - I must finally admit - is language. Without getting mired in a huge discussion about the definition of language, I will simply say that speaking languages is what we mostly do.
For a fascinating look at what we can learn about human language from creating them, check out this feature article from one of UCSD's newsletters. If you're a fan of StarTrek or the Lord of the Rings/Hobbits, you may have wondered if the strange languages spoken were just mindless, entertaining babble. Actually, they weren't. A lot of energy and creativity has gone into inventing languages for movies.
If you want to follow up on Klingon, or be one of the first in your neighborhood to speak it, there are books and websites to teach you, such as the Klingon Language Institute. Goodreads even has a page devoted to the best books on Klingon and other invented tongues.