Introduction to d-wave superconductivity

The establishment of d-wave superconductivity in hole-doped high-$Tc$ cuprates is perhaps the most important single event after the discovery of these systems by Bednorz and Müller in 1986. Here I recall first some basic properties of d-wave superconductors mostly based on the weak-coupling theory. Admittedly the weak-coupling cannot make any quantitative prediction. But I believe it is very important to know the applicability and the limit of the weak-coupling theory. I close this series of lectures with speculation where all these things are heading.