A shear is a transformation in which all points of an object slide parallel to a fixed line. A shear keeps all straight lines straight.
![A rectangle undergoing a shear. The base of the rectangle remains stationary, and the top of the rectangle moves to the right, parallel to the base, turning the rectangle into a parallelogram.](/glossary/shear/images/shear.png)
A shear is a transformation in which all points of an object slide parallel to a fixed line. A shear keeps all straight lines straight.