Trees are useful for modeling data that has a hierarchical relationship which moves in the direction from parent to child. No child node will have more than one parent.
To recap some terms:
root: A node which has no parent. One per tree.
parent: A node which references other nodes.
child: Nodes referenced by other nodes.
sibling: Nodes which have the same parent.
leaf: Nodes which have no children.
level: The height or depth of the tree. Root nodes are at level 1, their children are at level 2, and so on.
That was a lot of theory! Trees are beneficial and you’ll find they come up all the time as a useful way of modeling hierarchical data.