  This paper is an introduction to the use of the cobordism of chain complexes
with Poincar\'e duality in surgery theory. It is a companion to the author's
paper "An introduction to algebraic surgery" math.AT/0008071 (to appear in
Volume 2 of Surveys in Surgery Theory, Ann. of Maths. Studies, Princeton, 2001)
which is an introduction to algebraic surgery using forms and formations.
