A random graph is a graph in which properties such as the number of graph vertices, graph edges, and connections between them are determined in some random way. The graphs illustrated above are random graphs on 10 vertices with edge probabilities distributed uniformly in .
Erdős and Rényi (1960) showed that for many monotone-increasing properties of random graphs, graphs of a size slightly less than a certain threshold are very unlikely to have the property, whereas graphs with a few more graph edges are almost certain to have it. This is known as a phase transition (Janson et al. 2000, p. 103). Almost all graphs are connected and nonplanar (Skiena 1990, p. 156).
The Wolfram Language command RandomGraph[n, m] gives a pseudorandom graph with vertices and edges.