introductory (adj.)

late 14c., "act of bringing into existence," from Old French introduccion (14c.) and directly from Latin introductionem (nominative introductio) "a leading in," noun of action from past-participle stem of introducere "to lead in, bring in; introduce; found, establish; bring forward (as an assertion)," from intro- "inward, to the inside" (see intro-) + ducere "to lead" (from PIE root *deuk- "to lead").

Meanings "initial instruction in a subject" and "an introductory statement" are from mid-15c.; meaning "elementary treatise on some subject" is from 1520s. The sense of "formal presentation of one person to another" is from 1711.