Binary Tree
A binary tree is a tree in which every node has at most two children, conventionally called the left child and right child. There is no requirement that values be ordered, so a binary tree is not necessarily a Binary Search Tree.
Each node has zero, one, or two children.
Children are distinguished as left and right.
Values do not need to follow any ordering rule.
Traversal can be performed using inorder, preorder, postorder, or level order.