Tilt-shift Photography

View camera users usually distinguish between rotating the lens about a horizontal axis (tilt), and rotation about a vertical axis (swing); small- and medium-format camera users often refer to either rotation as "tilt".
Shift
In a subject plane parallel to the image plane, parallel lines in the subject remain parallel in the image. If the image plane is not parallel to the subject, as when pointing a camera up to photograph a tall building, parallel lines converge, and the result sometimes appears unnatural, such as a building that appears to be leaning backwards.