Language

A language is a structured system of communication used by humans, based on speech and gesture (spoken language), sign, or often writing. The structure of language is its grammar and the free components are its vocabulary. Many languages, including the most widely-spoken ones, have writing systems that enable sounds or signs to be recorded for later reactivation. Human language is unique among known systems of animal communication in that it is not dependent on a single mode of transmission (sight, sound etc.), it is highly variable between cultures and across time, and affords a much wider range of expression than other systems. It has the properties of productivity and displacement, and relies on social convention and learning. Languages evolve and diversify over time, and the history of their evolution can be reconstructed by comparing modern languages to determine which traits their ancestral languages must have had in order for the later developmental stages to occur. A group of languages that descend from a common ancestor is known as a language family; in contrast, a language that has been demonstrated to not have any living or non-living relationship with another language is called a language isolate. There are also many unclassified languages whose relationships have not been established, and spurious languages may have not existed at all.

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