Proto-Indo-European

Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European language family, the source from which languages such as Sanskrit, Ancient Greek, Latin, Old Church Slavonic and the Germanic branch that produced English all descend. It has no direct written record; its sounds, grammar and vocabulary are inferred entirely by comparing its many attested daughter languages, a method whose reconstruction irregularities led to the laryngeal theory, explaining them as the trace of vanished sounds.