The ozone in the global troposphere and stratosphere plays several important roles in affecting humanity and other living organisms on Earth. Ozone is important as an absorber of solar ultraviolet radiation, preventing biologically harmful levels of ultraviolet (UV) radiation from reaching the Earth's surface. Ozone is also a greenhouse gas and its global distribution plays an important role in determining the Earth's climate. In recent years, it has become progressively clearer that human activities may be affecting the amount of ozone in the global atmosphere. Atmospheric measurements now indicate that the amount of ozone in the stratosphere is decreasing, while the amount of ozone in the global troposphere, the atmosphere below about 10 km altitude, appears to be increasing. Overall, the vertically integrated amount of ozone, referred to as the total ozone column, is decreasing. Understanding the changes occurring to ozone and determining the appropriate societal response present important challenges to scientists and to policymakers. In,this paper, we review the current scientific understanding of global atmospheric ozone and the changes occurring in its distribution. We also examine the response that governments are making to the changes occurring in ozone.