What is the depth of a node (depth)?

A node's depth is the distance from the root to that node, measured as the number of edges between them.

Formally:

• The root's depth = 0 (since there are 0 edges from the root to itself).
• The depth of any other node = the depth of its parent + 1.

Example:

• A → depth 0
• B, C → depth 1
• D, E → depth 2

Difference from height:

• Depth is how many steps you take down from the root to a node.
• Height is how many steps up from a node to the deepest leaf.

Summary: A node's depth shows how deep it is in the tree relative to the root.