Defensive gun use (DGU) is the use or presentation of a firearm for self-defense, defense of others or, in some cases, protecting property. The frequency of incidents involving DGU and their effectiveness in providing safety and reducing crime are controversial issues in gun politics and criminology, chiefly in the United States.[1]: 64 Different authors and studies employ different criteria for what constitutes a defensive gun use which leads to controversy in comparing statistical results. Perceptions of defensive gun use are recurring themes in discussions over gun rights, gun control, armed police, open and concealed carry of firearms.