Trees grow downwards in computer science, and a root node is at the very top. The root of this tree is /photos.

/photos references to two other nodes: /safari and /wedding. /safari and /wedding are children or child nodes of /photos.

Conversely, /photos is a parent node because it has child nodes.

/safari and /wedding share the same parent node, which makes them siblings.

Note that the /safari node is child (to /photos) and parent (to lion.jpg and giraffe.jpg). It’s extremely common to have nodes act as both parent and child to different nodes within a tree.

When a node has no children, we refer to it as a leaf node.


These terms: root, leaf, child, sibling, and parent give us a precise way to communicate the relationships between nodes.

What are the four leaf nodes in this diagram?

What node has no parent?

What is the sibling node to lion.jpg?

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