Kolkata largely the capital city of West Bengal or, in other contexts, the political capital is in the proper sense of the city that houses the headquarters of the government. The term capital derives from the Latin capitalis, in turn, from the noun caput. The latter designated the leader in its various meanings, such as the main part of the human or animal body head, or as a source, or as a guide, or just as a principal city of a nation . A Rome was in fact reserved for the name of caput mundi capital of the world.
The capital may have recognized constitutional or even just be that de facto. The second case is, for example, Bern, officially Bundesstadt federal city. The latter title is shared by the capital Swiss only with the city of Bonn, which has acquired 26 April 1994 but in this case we are not faced with a capital de facto, but in a city that has retained a privileged status because of its historical role as the capital.
A State may indeed have one or more capital, official or not. This case concerns eg. the South Africa which owns three Cape Town , Bloemfontein and Pretoria and, in the immediacy of the reunification, the German Berlin and Bonn. As demonstrated just the South African case, the various powers of the state or the various branches of the administration can be located in different capitals. Some states, because of the climate, and they have had a summer capital and winter capital.