Incarceration, put simply, is the act of being imprisoned. A person who is imprisoned is said to be incarcerated. Incarceration is commonly referred to as being in prison or jail, and it can happen for any number of reasons, most commonly for serious crimes and offenses.
In most instances, the term is used in a court of law when a person is convicted and receives jail time. Although it is not generally used at the time of a person's arrest, the term still applies. It is most often used with long-term jail terms (three months or more). In the instance of refugees in a refugee camp, the term incarceration is also used, because it broadly covers being confined against your own will.