The Ministry of Magic
The Ministry of Magic is a government organization in the Harry Potter series that governs witches, wizards, magical beasts (start shameless plug See Fantastic Beasts and where to find themEnd Shameless plug), etc.
Individual ministries belong to separate countries, so the M.O.M. most talked about in Harry Potter is the British one. In some books, the Ministry seems to have ties to the conventional government, although in others it's independent.
There are around 8 or 9 different departments/divisions, each dealing with different aspects of the magical world. For instance, The Department for Regulation and Control of Magical Beasts takes care of all the little wizardly beasties that need to be hidden from muggles.
The ministry seems very bureaucratic to me, with hundreds of people just (as far as I can tell) doing busywork. However, quite a portion of Wizards seem to work for them.
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