A cliff is any very steep slope that has been formed by natural processes. Cliffs are too steep for soil and cliffs are always bare.

Cliffs may be created by rivers as they undercut their banks. These cliffs - called river cliffs - will be on the outside of the curving section (meander) of a river and may be from a few m to hundreds of m high.

Cliffs are also formed when rivers cut swiftly into the land to create gorges or canyons.