Language may refer either to the specifically human capacity for acquiring and using complex systems of communication, or to a specific instance of such a system of complex communication. The scientific study of language in any of its senses is called linguistics.
The approximately 3000–6000 languages that are spoken by humans today are the most salient examples, but natural languages can also be based on visual rather than auditory stimuli, for example in sign languages and written language. Codes and other kinds of artificially constructed communication systems such as those used for computer programming can also be called languages. A language in this sense is a system of signs for encoding and decoding information. The English word derives ultimately from Latin lingua, "language, tongue", via Old French. When used as a general concept, "language" refers to the cognitive faculty that enables humans to learn and use systems of complex communication.