This book is a publication in Swiss Seminars, a subseries of Progress in
Mathematics. It is an expanded version of the notes from a seminar on
intersection cohomology theory, which met at the University of Bern,
Switzerland, in the spring of 1983. This volume supplies an introduction to the
piecewise linear and sheaf-theoretic versions of that theory as developed by M.
Goresky and R. MacPherson in Topology 19 (1980), and in Inventiones Mathematicae
72 (1983). Some familiarity with algebraic topology and sheaf theory is assumed.