have if you look at the figureit becomes evident that the inner nodes contain operators while leaf nodes have operands we know that there are two types of nodes in the tree inner nodes and leaf nodes the leaf nodes are such nodes which have left and right subtrees as null you will find these at the bottom level of the tree the leaf nodes are connected with the inner nodes so in treeswe have some inner nodes and some leaf nodes in the above diagramall the inner nodes (the nodes which have either left or right child or bothhave operators in this casewe have or as operators whereas leaf nodes contain operands only abcdefg this tree is binary as the operators are binary we have discussed the evaluation of postfix and infix expressions and have seen that the binary operators need two operands in the infix expressionsone operand is on the left side of the operator and the other is on the right side supposeif we have operatorit will be written as howeverin case of multiplicationwe will write as * we may have unary operators like negation (-or in boolean expression we have not in this examplethere are all the binary operators thereforethis tree is binary tree this is not the binary search tree in bstthe values on the left side of the nodes are smaller and the values on the right side are greater than the node thereforethis is not bst here we have an expression tree with no sorting process involved this is not necessary that expression tree is always binary tree suppose we have unary operator like negation in this casewe have node which has (-in it and there is only one leaf node under it it means just negate that operand let' talk about the traversal of the expression tree the inorder traversal may be executed here