Wikipedia - Serie D

Serie D (Italian pronunciation: [ˈsɛːrje ˈdi]) is the top level of the Italian non-professional football association called Lega Nazionale Dilettanti. The association represents over 12,000 football players and 400 football teams across Italy. Serie D ranks just below Serie C (the third and last professional league since 2014–15), and is thus considered the fourth-ranked league in the country. It is organized by the Roman Comitato Interregionale (Interregional Committee), a "league in the league" inside the LND.