A mapping between two geometric figures is considered a transformation when it alters the position or orientation of a figure. Certain transformations, known as isometries, preserve both the shape and size of a figure. These isometries are the central topic. A transformation that produces a figure identical in size and shape to the original is a specific type. Examples include translations, rotations, and reflections. In translation, every point of a figure is moved the same distance in the same direction. In rotation, a figure is turned around a fixed point. Reflection creates a mirror image of the figure across a line.
The maintenance of size and shape is significant in numerous areas of mathematics and its applications. It ensures that measurements like lengths, angles, and areas remain unchanged throughout the transformation. This has uses, for instance, in architectural design, where precise replication of shapes is critical. Historically, the study of invariant properties under transformations has been a central theme in geometry, leading to the development of various geometric theories. The understanding of these transformations allows mathematicians and scientists to analyze and compare geometric figures rigorously.