As to whether detention counts as imprisonment, two legal terms must first be distinguished: 1. Detention is divided into administrative detention, criminal detention and judicial detention. Administrative detention and judicial detention are punitive measures, while criminal detention is a coercive measure. 2. Prison is a popular language, and its connotation includes various behaviors of being imprisoned, and sometimes refers to criminal punishment. 3. In criminal proceedings, pre-judgment detention (including criminal detention period and arrest detention period) can be used to offset the sentence. Legal basis: Article 47 of the "Criminal Law" stipulates that the calculation of fixed-term imprisonment and the term of fixed-term imprisonment shall be calculated from the date of execution of the judgment; if a person is detained before the execution of the judgment, one day of detention shall be reduced to one day of imprisonment. The above is the answer to whether criminal detention is in a detention center.