A polygon that has all sides the same measure and all angles the same measure is called a regular polygon.
In geometry, a regular polygon is defined by its equal-length sides and equal-measure angles, which gives it a harmonious symmetry. For example, a regular triangle (equilateral triangle) has all three sides of equal length and all angles measuring 60 degrees. Similarly, a regular quadrilateral, known as a square, has four equal sides and four right angles. Regular polygons can be classified based on the number of sides they have, such as regular pentagons, hexagons, and so forth.