  Outflows from active galactic nuclei (AGN) are one of the fundamental
mechanisms by which the central supermassive black hole interacts with its host
galaxy. Detected in $\ge 50\%$ of nearby AGN, these outflows have been found to
carry kinetic energy that is a significant fraction of AGN power, and thereby
give negative feedback to their host galaxies. To understand the physical
processes that regulate them, it is important to have a robust estimate of
their physical and dynamical parameters. In this review we summarize our
current understanding on the physics of the ionized outflows detected in
absorption in the UV and X-ray wavelength bands. We discuss the most relevant
observations and our current knowledge and uncertainties in the measurements of
the outflow parameters. We also discuss their origin and acceleration
mechanisms. The commissioning and concept studies of large telescope missions
with high resolution spectrographs in UV/optical and X-rays along with rapid
advancements in simulations offer great promise for discoveries in this field
over the next decade.
