Illegal entry is the act of foreign nationals arriving in or crossing the borders into a country in violation of its immigration law. Human smuggling is the practice of aiding people in crossing international borders for financial gain, often in large groups. Human smuggling is associated with human trafficking. A human smuggler will facilitate illegal entry into a country for a fee, but on arrival at their destination, the smuggled person is usually free.[citation needed] Trafficking involves physical force, fraud, or deception to obtain and transport people, usually for enslavement or forced prostitution.