In geography, a bank is the land alongside a body of water.

A river bank can be divided into three zones: Toe zone, bank zone, and overbank area. The toe zone is the area which is most susceptible to erosion. Because it is located in between the ordinary water level and the low water level, it is strongly affected by currents and erosional events.

The bank zone is above the ordinary high water level, but can still be effected periodically by currents, and gets the most human and animal traffic.

The overbank area is inland of both the toe and bank zones, and can be classified as either a floodplain or a bluff, depending on its slope. A river bank will respond to erosional activity based on the characteristics of the bank material. The most common type of bank is a stratified or interstratified bank, which consists of cohesionless layers interbedded with cohesive layers. If the cohesive soil is at the toe of the bank, it will control the retreat rate of the overlying layer. If the cohesionless soil is at the toe of the bank, these layers are not protected by the layers of cohesive soil. A Bedrock bank is usually very stable and will experience gradual erosion. A cohesive bank is highly susceptible to erosion in times of lowering water levels due to its low permeability.[2] Failures in cohesive soils will be in rotational or planar failure surfaces, while in non-cohesive soils failures will be in an avalanche fashion.