see http://depfind.sourceforge.net/Manual.html#Dependencies:
... a dependency is when the functioning of one element A requires the presence of another element B. We say that A depends on B and we write it:
A --> B
We say that A has an outbound dependency while B has an inbound dependency. It is the same dependency, but whether it is inbound or outbound is relative to how you look at it. We also say that A is a dependent and B is dependable.
A dependency graph comprises nodes for software artifacts linked together using two types of relationships.
Artifacts are packages, classes, and features. We use the term feature to designate class attributes, constructors, and methods; we will be treating them the same from here on. For the purpose of analyzing dependencies, we do not distinguish between different types of features, whether they are constructors or regular methods, and regardless of the feature's characteristics, such as being marked as final or static.
The first type of relationship is composition. Packages have classes, which themselves have features. We call this kind of "has a" relationship composition. A feature node is linked to its class node through composition. A class node is also linked to its package node through composition.
The second type of relationship is dependency. Classes refer to each other, features refer to each other, and features refer to classes. We call this kind of relationship dependency. Each node is linked to various other nodes of various type using dependency links.