nodes edges figure general (non-binarytree in computer programsnodes often represent such entities as peoplecar partsairline reservationsand so on--in other wordsthe typical items we store in any kind of data structure in an oop language like java these real-world entities are represented by objects the lines (edgesbetween the nodes represent the way the nodes are related roughly speakingthe lines represent convenienceit' easy (and fastfor program to get from one node to another if there is line connecting them in factthe only way to get from node to node is to follow path along the lines generallyyou are restricted to going in one direction along edgesfrom the root downward edges are likely to be represented in program by referencesif the program is written in java (or by pointers if the program is written in or ++typicallythere is one node in the top row of treewith lines connecting to more nodes on the second roweven more on the thirdand so on thustrees are small on the top and large on the bottom this may seem upside-down compared with real treesbut generally program starts an operation at the small end of the treeand it' (arguablymore natural to think about going from top to bottomas in reading text there are different kinds of trees the tree shown in figure has more than two children per node (we'll see what "childrenmeans in moment howeverin this we'll be discussing specialized form of tree called binary tree each node in binary tree has maximum of two children more general treesin which nodes can have more than two childrenare called multiway trees we'll see an example in trees and external storage tree terminology many terms are used to describe particular aspects of trees you need to know few of them so our discussion will be comprehensible fortunatelymost of these terms are related to real-world trees or to family relationships (as in parents and children)