In a world that's not really accustomed to H-bombs, North Korea's claim that it has detonated one may have you asking what it is, and how it's different from an A-bomb. Here's what you need to know about the nuclear bomb lingo that has fallen out of the conversation since the end of the Cold War:
Nuclear bombs:
Nuclear weapons create powerful explosions by splitting or fusing atoms' nuclei, releasing destructive amounts of energy.
The United Nations calls these bombs the "most dangerous" weapons in the world, and warns they have the possibility to kill millions, destroy cities and the environment, and cause "long-term catastrophic effects."
The A-bomb, or atomic bomb
The United States dragged the world into the age of nuclear weaponry in 1945, when it dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki.
The effects were devastating. Together, the bombs killed some 200,000 people, destroyed the cores of the cities and left behind harmful radiation.
The blasts also launched a new age of weaponry, and led to a tense arms race between the U.S. and the Soviet Union.
How it works
A-bombs use fission, or atom splitting, to produce explosions.
The reaction is triggered by bombarding radioactive elements' nuclei with fast-moving neutron particles, the Union of Concerned Scientists, a U.S.-based group founded at MIT in 1969, says.
This initial splitting sends off secondary neutrons, triggering a chain reaction as they bombard other nearby nuclei, causing them to split as well.
Each successive reaction doubles the amount of neutrons and energy released, the union explains.
In Hiroshima and Nagasaki, this amounted to explosions equivalent to 15 to 20 kilotons of TNT.
The H-bomb/hydrogen bomb/thermonuclear weapons
First developed in the United States in the 1950s, the hydrogen bomb is a far more powerful form of nuclear weapon.
Also known as the "superbomb," experts say hydrogen bombs can create explosions 1,000 times more powerful than those created by atom bombs. And there is potential to develop H-bombs even more powerful than that.
H-bombs have never actually been used during a war, but the U.S., Russia, France, the U.K., and China are all known to possess these powerful weapons.
How it works
Rather than fission, H-bombs use fusion, or the fusing of atomic nuclei to create massive explosions.
The Union of Concerned Scientists breaks the process down into three separate reactions, which happen almost simultaneously:
First, there is a chemical explosion which forces atoms inwards, compressing them into a dense "plutonium pit."
Second, a neutron generator sends neutron particles into the pit to set off a fission chain reaction, splitting nuclei to create a "primary" explosion.
Then, the high temperature and pressure caused by the primary explosion triggers a fusion reaction, causing atomic nuclei to fuse and set off the final, massive explosion.
According to the union, the U.S. has used this technology to create warheads with explosive yields of several hundred kilotons.
With files from The Associated Press
