在图论中，一个图中一条道路（path）是一个顶点串行，使得从它的每个顶点有一条边到该串行中下一顶点。一条道路可能是无穷的，但有限道路有一个最先顶点，称为起点，和最后顶点，称为末点。两者都成为这条道路的端点。道路中其它顶点成为内点。一个圈是起点与末点相同的道路。注意到一个圈中起点的选取是任意的。

道路与圈是图论中的基本概念，在大部分图论教材中的绪论一节会介绍。例如参见 Bondy and Murty (1976)、Gibbons (1985) 或 Diestel (2005)、Korte et al. (1990) 包含了图中关于道路的更高等算法论题。

In graph theory, a path in a graph is a finite or infinite sequence of edges which connect a sequence of vertices which, by most definitions, are all distinct from one another. In a directed graph, a directed path (sometimes called dipath) is again a sequence of edges (or arcs) which connect a sequence of vertices, but with the added restriction that the edges all be directed in the same direction.