Title: What is Quantum Field Theory?

We will review the status of Quantum Field Theory (QFT) as the language of physics.  We will stress that despite enormous success and a lot of progress, we still do not have a completely satisfactory presentation of the theory.  In particular, QFT is not yet mathematically rigorous.   This will lead us to discuss the symmetries of QFT as associated with topological operators.  This modern view has generalized our ideas of symmetries and has led to many new results.