in‧tro‧duc‧to‧ry [only before noun]
said or written at the beginning of a book, speech etc in order to explain what it is about
the objectives described in the introductory chapter
as the chairman said in his introductory remarks
intended for people who have never done a particular activity before:
an introductory course in data processing
a special low price that is charged for a new product for a limited period of time:
Don't miss our introductory offer!