While there has been an increasing number of high-quality CCD/dispersive spectroscopic data for various types of outflows both in AGNs and XRBs, their physical conditions, including its launching mechanisms and global perspective, are yet to be understood well to date. Many attempts have been made in the past decades from both observations and theoretical calculations to better constrain the underlying physical quantities (e.g. columns, velocities and ionization state) that yield the observed spectra. As a promising acceleration mechanism, I will discuss some of the speculative as well as fundamental nature of magnetically-driven accretion-disk winds in genera addressing its weaknesses and strengths as a candidate model. Motivated by the recent state-of-the-art X-ray observations, for example, with Chandra/HETGS, I will further introduce some of the very interesting properties of the warm absorbers (WAs) and ultra-fast outflows (UFOs) in the context of the MHD-driven wind view. Most importantly, an ultimate question will be “How one can distinguish MHD-driven winds from the others?” and I would like to stimulate our discussion in this respect as well.
// by Adi