A tree is a hierarchical data structure made up of nodes. Each node has zero or more child nodes, which are below it in the tree (in computer science, unlike in nature, trees grow down, not up). The node of which a node is a child is called its parent node. The base node of the tree is called the root node. Nodes with no children are called leaf nodes. |

A tree is a hierarchical data structure made up of nodes. Each node has zero or more child nodes, which are below it in the tree (in computer science, unlike in nature, trees grow down, not up). The node of which a node is a child is called its parent node. A child has only one parent. If the tree has a single node without a parent, this node is called the root node (or root). Nodes with no children are called leaf nodes. |

See also binary tree, heap, ordered tree data structure. |

See also binary tree, heap, ordered tree data structure, hierarchical tree structure. |