your ID: 0199 First Name: Roberto Last Name: Maiolino Affiliation: INAF - Observatory of Rome Title: X-ray absorption in AGNs Authors: R. Maiolino Topic: 6 Session: oral Abstract: We will review our current understanding of gas absorption in AGNs, as traced by X-ray observations, as well as the implications for the physics of the circumnuclear medium. We will review the distribution of gaseous column densities among AGNs of different types as well as evidences for absorption variability. We will discuss the comparison between X-ray and optical/IR absorption. Finally, we will review our current constraints on the X-ray absorption properties in high redshift sources.