What does it mean that directed versus undirected relationships?

Some relationships have direction — A causes B is different from B causes A.

Example: On Twitter/X, following is directed: you can follow someone who does not follow you back. The relationship has an arrow — it flows from follower to followed. On Facebook, friendship is undirected: if A is friends with B, then B is necessarily friends with A. The connection has no arrow — it is mutual by definition. This single structural difference produces radically different network dynamics. Twitter's directed graph enables asymmetric influence — a person with millions of followers and zero following can broadcast without reciprocity. Facebook's undirected graph enforces mutual acknowledgment, creating denser clusters of bidirectional connection. The same people, the same devices, the same internet — but the direction (or absence of direction) in the relationship fundamentally changes the shape and behavior of the entire network.

Try this: Choose a system you participate in — your team, your family, your professional network, a project you manage. List ten relationships within that system. For each one, ask: does this relationship have a direction? Write an arrow (A -> B) for directed relationships and a line (A -- B) for undirected ones. Then look for asymmetries you hadn't noticed. Where did you assume mutual relationships that are actually one-directional? Where does information, authority, or influence flow in one direction but not the other? Identify at least two relationships you had been treating as undirected that are, on closer inspection, directed — and write down what changes when you acknowledge the arrow.