平面グラフは、エッジ（2点を接続する線）が互いに交差しない方法で描画できる接続グラフです。このような方法で描画すると、図面は平面グラフと呼ばれ、グラフ自体は平面グラフと呼ばれます。
A planar graph is a connected graph that can be drawn in a way that none of the edges (lines connecting two points) cross each other. When drawn in such a way, the drawing is referred to as a plane graph while the graph itself is referred to as a planar graph.