High-redshift active galactic nuclei and the next decade of Chandra and XMM-Newton

We briefly review how X-ray observations of high-redshift active galactic nuclei (AGNs) at z = 4–7 have played a critical role in understanding their basic demographics as well as their physical processes; for example, absorption by nuclear material and winds, accretion rates, and jet emission. We point out some key remaining areas of uncertainty, highlighting where further Chandra and XMM-Newton observations/analyses, combined with new multiwavelength survey data, can advance understanding over the next decade.