Direct Detection of Sub-GeV Dark Matter: Models and Constraints

I will make some general comments about the search for dark matter and other new particles, contrasting current research trends with those 10 years ago. I will then focus on recent ideas for direct detection experiments to search for dark matter with masses in the MeV-to-GeV range. I will then discuss briefly three topics: (i) the solar neutrino background (or "how low in cross section (interaction strength) can future direct-detection experiments probe before solar neutrinos become an irreducible background"), (ii) novel constraints on low-mass dark matter from Supernova 1987A, and (iii) strongly interacting dark matter (or "how large in cross section can direct-detection experiments probe before terrestrial effects stop sub-GeV dark matter from reaching the detector").