  In his 2011 paper, Teleman proved that a cohomological field theory on the
moduli space $\overline{\mathcal{M}}_{g,n}$ of stable complex curves is
uniquely determined by its restriction to the smooth part $\mathcal{M}_{g,n}$,
provided that the underlying Frobenius algebra is semisimple. This leads to a
classification of all semisimple cohomological field theories. The present
paper, the outcome of the author's master's thesis, presents Teleman's proof
following his original paper. The author claims no originality: the main
motivation has been to keep the exposition as complete and self-contained as
possible.
