Spoken language is believed to date back 50,000 to 100,000 years, and is considered to be one of the major things that distinguish humans from animals. It long predates Written Languages.
The languages with the largest number of native speakers are:
- Arabic languages
A major issue is that languages are collapsing as worldwide networking increases - the larger languages outstrip the smaller communities, and entire sets of languages are lost. A number of projects are underway to catalog these dying or disappearing languages.
Artificially constructed languages
In addition to the languages which have evolved naturally among humans, some languages have been artificially constructed, sometimes as part of fictional universes and other times intended for actual use in communication.
"Serious" artificial languages
"Fictional" artificial languages
- Beanish (xkcd) 
- Dothraki (Game of Thrones)
- Elvish (Tolkien)
- Klingon (Star Trek)
- Láadan (Native Tongue)
- Na’vi (Avatar)
- Orchish (JourneyQuest) 
- Pakuni (Land of the Lost)
- Simlish (The Sims)
- The Google Endangered Languages Project
- Songs in endangered languages
- How to Save a Dying Language
- Last Two Speakers of Dying Language Refuse to Talk to Each Other (No, that's not The Onion!)
- 8 Endangered Languages That Could Soon Disappear
- Xinjiang’s Xibe Authors: Inspired by “Language of Exile” that has Outlived Manchu
- Academics team up to save dying languages
- Evolution of Human Languages (etymological databases)
- What Shakespeare's plays originally sounded like
- Ancient languages reconstructed by computer program (BBC, 2013-02-12).
- Telling Tales in Proto-Indo-European (includes reconstructed audio)
- Utopian for Beginners: An amateur linguist loses control of the language he invented.
- Are Elvish, Klingon, Dothraki and Na’vi real languages? - John McWhorter
- Rickroll your friends or enemies in Klingon
- Vulgar: automatic language construction
- The Grammar Rules Behind 3 Commonly Disparaged Dialects
- American dialect maps
- The Tiny Island Where Men Have Their Own Language
- How the World's Newest 'Mixed' Language Was Invented
- Language: Wikipedia
- Language Log
- The Open Language Archives
- English-language studies 'destructive' to China's education, says CPPCC deputy
- E-Prime: version of English without 'to be'
- Open source speech recognition
- The Great Language Game
- Is 'Huh?' a universal word?
- How to speak and write postmodern
- Dolphin whistle instantly translated by computer
- Scientists reconstruct speech through soundproof glass by watching a bag of potato chips