# Data Structure Tree

Data Structure Tree is a hierarchical relationship between various elements. It is a set of one or more nodes and nodes are connected by an edge. Each node contains some value. The node is represented by a circle and edge lives connecting these nodes. Tree is a non linear data structure, which is very flexible, versatile and widely used. In the above tree, A is the root element and it has two subtree B and C. B is itself root element of D and E. And similarly C is the root element of F and G.

## Tree Terminology

These are the different terminology used in the tree.

• Leaf Node - Any node with degree 0 or that has no children is called a terminal node or leaf node.
• Level of Node - The level of any node is the length of its path from the root.
• Root Node - The topmost node of the tree.
• Sub Trees - The branches of the root node are called sub trees.
• Path - The sequence of the edges is called a path.
• Degree - The degree of the node is equal to the number of the children that a node has.

## Tree Types

These are the following six tree types.

1. General trees
2. Forests
3. Binary trees
4. Binary search trees
5. Expression trees
6. AVL Tree
7. B Tree