The word prefect can refer to any of a number of types of official, including:
in Latin, praefectus: a high-ranking military or civil official in the Roman Empire; the title now attaches to the heads of some departments of the Roman Curia, who are traditionally Cardinals, and if they are not are titled Pro-Prefect.
in the context of schools, a prefect is a pupil who has been given authority over other pupils in the school.
A prefect (préfet) is the State's representative in a région (thus called préfet de région) or département. His agency is called the préfecture. Sub-prefects (sous-préfets, sous-préfecture) operate in the arrondissements\ under his responsibility. The prefect of a région is also responsible for the département where his préfecture is seated, and the prefect of a département for the arrondissement where his préfecture is seated.
The prefects operate under the Minister of the Interior. Their main missions include.
representing the state before the local governments;
respect of legality: the services of the prefect control whether the decisions of local governments were legal and submit suspicious cases to administrative courts or financial auditing courts.