A more thorough explanation:

A gas chamber is a small, enclosed room where a person is executed by inhaling poisonous gas. The prisoner is strapped to a chair and the gas is released into the chamber until the person dies.

For example, during the Holocaust, Nazi Germany used gas chambers to kill millions of Jews and other minorities. In the United States, gas chambers were used as a method of execution in some states until the 1990s.

The use of gas chambers as a method of execution is controversial and has been criticized for being inhumane. Supporters argue that it is a quick and painless way to carry out the death penalty.