Street map as a graph

* what are the vertices?  intersections

* what are the edges?  roads

* are edges directional?  one-way streets

* what are the weights?   distance,  travel time

* are the weights fixed?  yes fixed,  no time-dependent



Facebook as a graph

* what are the vertices?   people/users

* what are the edges?   friends

* are edges directional?   no

* what are the weights?   not explicit

* are the weights fixed?  n/a