Tarjan
In plain terms
An algorithm for finding strongly connected components in a graph.
Going deeper
Tarjan's algorithm uses a single DFS with low-link values to identify groups of mutually reachable nodes in a directed graph. It's elegant and linear-time.
Under the hood
O(V+E) in one pass; low-link bookkeeping identifies SCC roots, also adaptable for bridges and articulation points.
Examples
Dependency cycles, deadlock detection, compiler analysis, social clustering.
Think of it like...
Like finding tight-knit friend circles where everyone can reach everyone else within the group.