Hi, this is the first time i write in English on my Blog. I am going to try to explain you how does work a BinaryTree for a JAVA's implementation.
The BinaryTree is an abstract data type. This data structure is constructed by another internal little structure called Node. Every Node has two sons, the left son and the right son, who are Nodes too. This parental relationship is the base of the BinaryTree's hierarchy.
The Father node in the top of the BinaryTree is the root, and the son node in the bottom of the BinaryTree or who has not son, are the leafs.
In the next picture we can watch this structure: