# A tree in data structure

is a finite non empty sets of element, one of these elements is called the root and remaining elements are partition into trees which are called sub tree of tree.

**OR**

In other words a tree is a collection of mode and each node is linked with other nodes with the help of branch. The nodes are connected in such a way that they have no loops and there is a special node called the root.

**OR**

A tree is a cyclic simple, connected graph. A tree contains no loop and no cycle.

There is no more than one edge between any pair of nodes.

## Tree terminology

**Node ** each element of a tree is called node.

**Root ** it is the first node in the hierarchical arrangements of data items in the above tree a is the root node.

**Parent** parent of a node is the immediate predecessor of a node.

Example – here B is the parent of D and E.

**Child** each immediate successor of a nodes is known as child. in the above figure B and C is the child of A.

**Swiveling** the child node of a given parents code is called swiveling.