Symmetry refers to a balanced and proportional arrangement of parts in an object or shape. When an object can be divided into two identical halves, it is said to have line symmetry. There are also other types, such as rotational symmetry, where an object looks the same after a certain degree of rotation. Transformations involve changing the position or size of a shape in a plane. Common transformations include translation, where a shape moves without changing its form; rotation, where a shape turns around a point; and reflection, where a shape is flipped over a line. These concepts are fundamental in geometry and art.