Heavy fermion superconductors: immediate family and other relatives

Heavy fermion superconductors were the earliest studied electronic systems where correlations lead to unconventional pairing, and remain the broadest family of such compounds. Yet the very breadth of the observed behaviors makes it critical to decide what features are idiosyncrasies of a specific family member, and which ones have common origin across the entire family and possibly connect with more distant relatives in the unconventional superconductor family such as cuprates, iron, or organics. What is the role of traditional Kondo and Mott physics, frustration, quantum critical fluctuations, hidden orders, composite and multicomponents order parameters, electronic nematicity, in determining the superconducting phases? Do we understand what aspects play the dominant role for superconductivity in different families and why? Is there a broader consensus on what the important questions and answers are? I will review the current status of the field emphasizing the common trends and open questions within several families of heavy fermion compounds, and make connection with other systems.