Binary trees are an important data structure in computer science. They are often used for search, priority queues, and databases. They are efficient because they are easy to traverse in a concurrent fashion. Go has great concurrency primitives (which we'll discuss in Chapter 3, Understanding Concurrency) that allow us to do this in a simple manner. Being able to use goroutines and channels to walk a binary tree can help speed up how we traverse a grouping of hierarchical data. A balanced binary tree can be seen in the following diagram:

A couple of special binary trees are as follows:

• Full binary tree: Every node sans the leaf nodes has 2 child nodes.
• Complete binary tree: A tree that is completely filled, sans the bottom layer. The bottom layer must be filled from left to right.
• Perfect binary tree: A complete binary tree in which all the nodes have two children and all the leaves of the tree are at the same level.