Superconductivity has been one of the grand challenges of condensed matter physics and quantum many-body theory since before either field had a name.  It is the most striking of all macroscopic quantum phenomena, in which all the electrons in a  sample of metal spontaneously pair and condense in a coherent quantum state.  I will review the phenomenology and microscopic theory of conventional electron-phonon superconductivity before introducing more modern topics related to unconventional pairing by exchange of electronic excitations.   The course will include extensive discussion of experimental techniques, and give examples from cuprates, Fe-based superconductors, and heavy fermion superconductors