Deciphering connected components in a directed graph is a bit more difficult
than it is in undirected graphs. A *strongly connected component* is a
subsection of a directed graph in which there is a directed path from every
vertex to every other vertex. The rather convoluted graph below demonstrates the
concept.

If each strongly connected component is treated as a single node, the graph
becomes a directed acyclic graph. Just like nodes in a directed graph, a
strongly connected components with no incoming edges is known as a *source* and
one without any outgoing edges is known as a *sink*.