In geography and geology, a cliff is a vertical, or near vertical, rock exposure. Cliffs are formed as erosion landforms due to the processes of erosion and weathering that produce them. Cliffs are common on coasts, in mountainous areas, escarpments and along rivers. Cliffs are usually formed by rock that is resistant to erosion and weathering. Sedimentary rocks most likely to form cliffs include sandstone, limestone, chalk, and dolomite. Igneous rocks such as granite and basalt also often form cliffs.

The Community-Led Infrastructure Finance Facility or CLIFF is a finance facility created in 2002, and providing bridge finance and venture capital for housing and infrastructure (especially water and sanitation) in developing countries. It is coordinated by Homeless International, with most of the funding coming from DFID and SIDA.