Corresponding sides refer to the pairs of sides in two or more geometric figures that are in the same relative position. For example, in two similar triangles, the sides that occupy the same position are called corresponding sides. This means that if one triangle has a side that is opposite to a certain angle, the other triangle will have a side opposite to its corresponding angle.
In the case of similar figures, corresponding sides are proportional, meaning the ratio of the lengths of corresponding sides is constant. This property is crucial in geometry, especially when dealing with similarity and congruence, as it helps in understanding relationships between shapes.