A concentration camp (or internment camp) is a place where a government forces people to live without trial. Usually, those people belong to groups the government does not like. The term means to confine (keep in a secure manner) "enemy citizens in wartime or terrorism suspects".
Some governments put people in concentration camps because they belong to a certain religion, race, or ethnic group.
Usually, people are sent to concentration camps without having had a trial or being found guilty of a crime.
Sometimes, governments send people to concentration camps to do forced labor or to be killed. For example, concentration camps were run by Nazi Germany and the Soviet Union during World War II. The Nazis used concentration camps to kill millions of people in The Holocaust and force many others to work as slaves. However, many other countries have used concentration camps during wars or times of trouble.