Most common naming for graph edges ("to $\to$ from" vs "in $\to$ out" vs "source $\to$ target", etc)

Question

Within the world of graph theory when discussing and documenting a graph structure, which is the most common terminology used to describe the edge relationship between the nodes?

So far, we have the following options under discussion:

$$\begin{align} \text{to} &\to \text{from} \\ \text{in} &\to \text{out} \\ \text{source} &\to \text{target} \end{align}$$

Answer 1

To me (with little formal graph theory education) those three things signify slightly different things. This is what my gut says:

• To-From: For a pair of vertices, there can be an edge going from one and to the other
• In-Out: For a given vertex, some edges go in, some edges go out
• Source-Target: For a given edge, one vertex is the source, and one vertex is the target