  These are notes of a series of lectures on mirror symmetry and topological
string theory given at the Mathematical Sciences Center at Tsinghua University.
The N=2 superconformal algebra, its deformations and its chiral ring are
reviewed. A topological field theory can be constructed whose observables are
only the elements of the chiral ring. When coupled to gravity, this leads to
topological string theory. The identification of the topological string A- and
B-models by mirror symmetry leads to surprising connections in mathematics and
provides tools for exact computations as well as new insights in physics. A
recursive construction of the higher genus amplitudes of topological string
theory expressed as polynomials is reviewed.
