The largest use of geotextiles in civil engineering, in terms of the total area of material used, is for separation. Yet it is one of the most difficult of geotextile functions to define and describe. This set of technical notes was prepared in order to provide guidance on specific aspects of design, construction and use of geotextile separators. The authors of the notes are well known members of the profession with a combined experience of more than a hundred years of geotextile design. This note introduces the subjects covered in the set of notes and highlights the lessons which may be learned from them. Since the early stages of geotextile engineering it has been considered that the three main functions of a geotextile are
(a) filtration
(b) separation
(c) reinforcement.
