Isometry

An isometry is a transformation that preserves distances and angles, meaning the shape and size of an object remain unchanged. Think of it as moving, rotating, or reflecting an object without stretching or shrinking it. For example, sliding a picture across a wall or flipping it over are isometries—they change the position or orientation but keep the object's dimensions exactly the same. This concept is fundamental in geometry because it helps us understand when two shapes are essentially the same in size and form, just in different positions or orientations.