I am trying to understand the way in which Table Models work by doing the tutorials provided by Qt, I am facing the problem that I am not able to understand the following code lines:

int rowCount(const QModelIndex &parent = QModelIndex())const override;

Your are declaring a method (rowCount) and passing it a const of type QModelIndex pointing to a memory address (&parent) and why is equal to QModelIndex? for me this makes no sense, why pass a memory address to (neither know what parent really means or where it is, I guess it is the parent class).

Can someone (please), explain me this code?

Thank you!