The way of arranging files or folders with the name of correspondents in drawers or cabinets in alphabetical order is called alphabetical classification.
The way of filing under which the files of the individuals or organizations are arranged in the drawer in the numerical order as 1, 2, 3, 4, etc. is called numerical classification.
The way of arranging files in a drawer or cabinet according to the subject of the document is called subject classification.
The way of arranging files in a drawer or cabinet on the basis of geographical regions is called geographical classification.