• a set of vertices are a connected component in an undirected graph if any vertex in the set can be reached by any other vertex in the set by traversing edges
• they become a strongly connected component (SCC) when the above rule applies in a directed graph
• Tarjan’s algorithm is used to find SCCs in $\mathcal{O}(V+E)$ using only one $\text{DFS}$ iteration

Tarjan’s Algorithm