study of the forms of land surfaces

Topography means the description of shape. The word comes from Greek: τόπος "place" and γράφω "(I) write". It is an important part of earth science.

When you talk of the topography of the land, you refer to the landscape features like valleys, hills and mountains, rivers and lakes, or the coastline. Everything that describes the form of the landscape, is part of the topography. Topographic maps show topography.