In the United States, gun control is a topic that is always being talked about. Some people want more freedom with guns, and others feel that gun laws should be more restrictive. Every time a school shooting, or tragedy having to do with guns, happens more laws are passed, but they do little to prevent the next event that is inevitable.
Some of the gun laws that the U.S. has right now include: you have to be at least 18 to buy a gun, and fugitives, people who are deemed a danger to society, people involuntarily admitted into mental institutions, and people with felony convictions are restricted from buying guns and owning them.
Most states require permits to own a handgun. They also run a background check on you before you can buy the gun, although sometimes the background checks are not thorough enough to keep guns out of the hands of people planning to do harm with them. In the South, gun laws tend to be more loose, and in the North, they tend to be more restrictive.
In the past 10-20 years school shootings, and attempted school shootings, have become a big issue. The first school shooting was on April 20, 1999, when two boys named Eric Harris and Dylan Klebold shot up Columbine High School in Littleton, Colorado. They killed 13 people and injured 20.

The school shooting of Sandy Hook Elementary, I think, sent the most shockwaves across the nation.
The last school shooting to happen, was at Parkland High School in Florida. 17 lost their lives, and their classmates are taking a stand because they feel that gun control laws need to be passed so more innocent lives can be saved. There have been laws/policies passed to make it harder to obtain guns including: in some stores the age to buy guns has been raised to 21, background checks are getting more thorough, and bump stocks are being banned in some states. Only time will tell if these laws are going to be effective.
For more information please visit:
https://gun-control.procon.org/
http://time.com/5169210/us-gun-control-laws-history-timeline/