In geometry, a parallelogon is a polygon with parallel opposite sides (hence the name) that can tile a plane by translation (rotation is not permitted).^[1][2]

Parallelogons have an even number of sides and opposite sides that are equal in length. A less obvious corollary is that parallelogons can only have either four or six sides;^[1] Parallelogons have 180-degree rotational symmetry around the center.

A four-sided parallelogon is called a parallelogram.

The faces of a parallelohedron (the three dimensional analogue) are called parallelogons.^[2]

Quadrilateral and hexagonal parallelogons each have varied geometric symmetric forms. They all have central inversion symmetry, order 2. Every convex parallelogon is a zonogon, but hexagonal parallelogons enable the possibility of nonconvex polygons.

More information Sides, Examples ...

Sides	Examples		Name	Symmetry
4			Parallelogram	Z2, order 2
			Rectangle & rhombus	Dih2, order 4
			Square	Dih4, order 8
6			Elongated parallelogram	Z2, order 2
			Elongated rhombus	Dih2, order 4
			Regular hexagon	Dih6, order 12

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A parallelogram can tile the plane as a distorted square tiling while a hexagonal parallelogon can tile the plane as a distorted regular hexagonal tiling.