Quasars are among the most powerful and luminous objects in the Universe. As such, they can be found and studied in detail far back into the epoch of reionization at redshifts z>6. These luminous quasars are ideal laboratories to study the build-up of the first massive galaxies and black holes and the onset of small- and large-scale structures in the early Universe. I will review our "pre-JWST" knowledge of the physical properties of the most distant quasars (black holes, host galaxies, and their environment). I will also highlight recent results, including from JWST, and briefly describe what to expect from the European Euclid mission. The next few years will be critical for advancing our understanding of quasars at cosmic dawn.