This book is a collection of expository articles based on four lecture series presented during the 2012 Notre Dame Summer School in Topology and Field Theories.

The four topics covered in this volume are: Construction of a local conformal field theory associated to a compact Lie group, a level and a Frobenius object in the corresponding fusion category; Field theory interpretation of certain polynomial invariants associated to knots and links; Homotopy theoretic construction of far-reaching generalisations of the topological field theories that Dijkgraf and Witten associated to finite groups; and a discussion of the action of the orthogonal group O(n) on the full subcategory of an n-category consisting of the fully dualisable objects.

The expository style of the articles enables non-experts to understand the basic ideas of this wide range of important topics.