Informally, a graph is a set of objects called vertices (or nodes) connected by links called edges (or arcs), which can also have associated directions. Typically, a graph is depicted as a set of dots (i.e., vertices) connected by lines (i.e., edges), with an arrowhead on a line representing a directed arc.
Such graphs can be used to represent and analyze a variety of systems and problems, including colorability problems, shortest path algorithms and spanning trees.
