until all nodes are traversed step recursively traverse left subtree step visit root node step recursively traverse right subtree pre-order traversal in this traversal methodthe root node is visited firstthen the left subtree and finally the right subtree we start from aand following pre-order traversalwe first visit itself and then move to its left subtree is also traversed pre-order the process goes on until all the nodes are visited the output of pre-order traversal of this tree will be - - - - - - algorithm until all nodes are traversed step visit root node step recursively traverse left subtree step recursively traverse right subtree