Upazila (Bengali: উপজেলা, lit. 'sub-district' pronounced: upojela), formerly called thana (Bengali: থানা), is a geographical region in Bangladesh used for administrative or other purposes. They function as sub-units of districts. Their functionality can be seen to be analogous to that of a county or a borough of Western countries.
Bangladesh, at present, has 490 upazilas (as of 9 May 2016). The upazilas are the second lowest tier of regional administration in Bangladesh. The administrative structure consists in fact in Divisions (8), Districts (64), Upazila/Thana and Union Parishads (UPs). This system of devolution was introduced by the former military ruler and President of Bangladesh, Lieutenant General Hossain Mohammad Ershad, in an attempt to strengthen local government.
Below UPs, villages (gram) and para exist, but these have no administrative power and elected members. The Local Government Ordinance of 1982 was amended a year later, redesignating and upgrading the existing thanas as upazilas.
Upazilas were formerly known as thana which literally means police station. Despite the meaning, thanas functioned much as an administrative and geographic region, much as today's upazilas. In 1982 thanas were re-termed to as upazilas with provisions for semi-autonomous local governance. This system was reverted to the thana system in 1992. Later in 1999 geographic regions under administrations of thanas were converted into upazilas. All administrative terms in this level were renamed from thana to upazila. For instance, Thana Nirbahi Officer (lit.Thana Executive Officer) was renamed to upazila Nirbahi Officer (lit.upazila Executive Officer). The word thana is now used to solely refer to police stations. Generally, there is one police station for each upazila; but larger administrative units may have more than one police station covering different regions.