In which quadrilateral are the diagonals always congruent?

The diagonals of a rhombus are always congruent. A rhombus is a quadrilateral with all sides of equal length. Due to its symmetry, the diagonals of a rhombus bisect each other at right angles, and they are always of the same length. This property distinguishes a rhombus from other quadrilaterals like rectangles or parallelograms.