What is a node (node) in a tree?

A node is the basic element of a tree that stores data and references to other nodes.

Every node contains:

1. A value - the data itself (for example, a number, a string, an object).
2. A reference to its parent (except for the root).
3. References to child nodes (one or several).

Types of nodes:

• Root - a node with no parent; the tree starts from it.
• Internal nodes - have at least one child.
• Leaves - have no children.

Example:

Here:

• A, B, C, D are nodes,
• A is the root,
• D is a leaf,
• B is an internal node.

Summary: A node is the building block of a tree, storing the data and the links that define its structure.