Water is central to many of the process discussed in this book. Fluvial erosion on hillslopes is driven by overland flow during rainfall events. Soil weathering, vegetation and organic matter are driven by water in the soil profile. Accordingly a brief summary of the key aspects of hydrology that are important is warranted. Moreover there is a range of geomorphology concepts that have permeated through the landform evolution literature, either because they triggered many of the original approaches or because they have been found useful when studying (either experimentally or mathematically) landform evolution. This chapter will highlight the most important hydrology and geomorphology concepts in soilscape and landform evolution.