Full binary trees: A binary tree in which every node has 0 or 2 children is termed as a full binary tree.
Complete binary tree: A complete binary tree has all the levels filled except for the last level, which has all its nodes as much as to the left.
Perfect binary tree: A binary tree is termed perfect when all its internal nodes have two children along with the leaf nodes that are at the same level.
A degenerate tree: Each internal node has only one child.
Balanced binary tree: A binary tree in which the difference between the depth of the two subtrees of every node is at most one is called a balanced binary tree.