• Tree: A hierarchical structure used for organizing and searching data efficiently.
• Nodes: Fundamental units of the tree, connected by edges, forming a hierarchy.
• Root Node: The topmost node with no parent, starting point of the tree.
• Child Nodes: Nodes that descend from another node (parent).
• Leaf Nodes: Nodes with no children.
• Recursive Structure: Each node can have child nodes, and those child nodes can have their own children, forming a recursive hierarchy.

Key Terminologies:

1. Parent Node: The predecessor of any given node. (Example: {B} is the parent of {D, E})
2. Child Node: The immediate successor of a parent node. (Example: {D, E} are the children of {B})
3. Root Node: The node at the top of the tree, without any parent. (Example: {A})
4. Leaf Node (External Node): Nodes without any children. (Example: {I, J, K, F, G, H})
5. Ancestor: Predecessor nodes along the path from the root to a given node. (Example: {A, B} are ancestors of {E})
6. Descendant: A node that is a child or below another node.
7. Sibling: Nodes that share the same parent. (Example: {D, E} are siblings)
8. Level of a Node: Number of edges from the root to the node. (Root node level = 0)
9. Internal Node: A node with at least one child.
10. Neighbor: The parent or child of a node.