Concord is the common interstellar auxiliary language and the official language of the Interstellar Community of Sovereign States. Humans developed it expressly for communication among peoples whose native languages, vocal organs, limbs and senses may differ profoundly. It circulates through diplomacy, trade, travel, administration and technical work.
Its origins lie in humanity's wider interstellar history, away from Earth. Native languages remain vital within the societies that use Concord, and fluency varies from person to person.
Spoken Concord uses sound distinctions chosen for the broadest practicable range of intelligent species. Speakers accommodate physiological variation while preserving shared meaning. Some species cannot produce or hear its spoken form reliably; signed and written communication provide other routes.
Signed Concord supports ordinary conversation, technical explanation and abstract debate. Broad limb gestures, movement, timing, direction, orientation and relative position carry meaning. Its signs do not depend upon fingers, thumbs or a particular appendage shape.
Different anatomies can produce equivalent signs where their movement permits. The signed form is a complete language, capable of institutional and philosophical discussion as well as practical exchanges. Those unable to make or perceive its gestures can use writing or appropriate communication interfaces.
Written Concord emphasizes distinguishable symbols, consistent rules and a manageable learning burden. It allows communication across vocal and gestural differences, with accessible interfaces adapting to a reader's senses and physical capabilities.
ICSS proceedings, correspondence and intergovernmental coordination use Concord as a shared medium. Interpreters remain important, and an instrument's adopted terms determine which treaty texts or translations have legal authority. Common language reduces the effort of crossing political and biological boundaries without removing every barrier.