Zigzag

A zigzag is a regular apeirogon whose vertices are co-planar but not co-linear. It may be considered a skew polygon even though it is co-planar.

As a Petrie polygon
Zigzags appear as Petrie polygons of several polyhedra, in particular in Euclidean tilings, such as the triangular tiling, square tiling, and the hexagonal tiling. As a result they appear as faces of the Petrie duals of these polyhedra: the Petrial triangular tiling, Petrial square tiling, and Petrial hexagonal tiling.

The zigzag also appears as a Petrie polygons in polyhedra made by gyroelongating along an apeirogon. For example a zigzag is one of the Petrie polygons of the apeirogonal antiprism (a gyroelongation of the apeirogonal dihedron). The zigzag then also appears as a face of their Petrie duals.

Truncated zigzags
There are truncated zigzags which are uniform but not regular formed by truncating or quasitruncating the zigzag.

Regular skew polygons
Just as the flat apeirogon can be viewed as the limit of regular $n$-gons as $n$ goes to infinity, the zigzag can be viewed as the limit of regular skew $n$-gons as $n$ goes to infinity. This results in the zigzag often being classified as a skew polygon despite it being planar.