Civilians in the United States own about 270 million guns, according to a 2007 report by the Switzerland-based Small Arms Survey. That's slightly more than the population of Indonesia, the world's fourth most-populated country. America ranks No. 1 in firearms per capita.
According to the FBI, 2015 was a record year for background checks
on guns. Some have pointed out the requests for background checks have gone up after mass shootings, the idea being that shootings cause people to worry about their safety and buy a gun to protect themselves. The month after the mass shooting at Sandy Hook Elementary School in Newtown, Connecticut, for example, saw a surge in requests for background checks. The terrorist attack in San Bernardino, California, had a similar effect.
Even though the homicide rate has fallen sharply in the last 50 years
The intense public focus on mass shootings and other killings belies a larger trend: The homicide rate has fallen sharply in the United States. The homicide rates for 2013 and 2014 were the lowest in more than 50 years. Firearms are used in roughly 7 in 10 killings, the FBI says.
Handguns are the weapons used most often in homicides
After many shootings, the focus immediately shifts toward restricting the use of AR-15s or other semiautomatic rifles. But statistics show that most murders in the United States are not a part of mass shootings, and handguns are the most common weapon.
Gun violence kills far more Americans than terrorism
During his presidency, Barack Obama has had to deliver statements on gun violence regularly. After a shooting at Oregon's Umpqua Community College in October, he asked news organizations to tally up the number of Americans killed by terrorist attacks in the last decade and compare it with the number of Americans who have died in gun violence.
Most U.S. gun deaths are suicides
Of the more than 400,000 people who died as a result of gun violence from 2001 to 2013, about three in five were from suicide. Just under two in five -- or about 156,000 people -- died of homicide.
Seven in 10 active shootings are in schools, businesses
Sandy Hook Elementary School in Newtown, Connecticut; a conference center in San Bernardino, California, where a holiday party was taking place; Mother Emanuel AME Church in Charleston, South Carolina -- these are some of the more public places that have seen major mass shootings.
Shooter incidents: Most take own life
The FBI studied 160 specific types of active-shooter incidents between 2000 and 2013. The study doesn't encompass all shootings, but gives insight into how some situations could end. Unlike a homicide or mass killing, the "active" aspect implies that both law enforcement and citizens have the potential to affect the outcome of the event based upon their responses.
This story first published on December 4, 2015. It has been updated to add additional graphics.