  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; e.g., 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.
