All These Three Tree Traversals: Preorder, Inorder and Postorder Traversals are Depth-First Traversals with the added condition that In All of them, in the Depth first Traversal, Left Node is processed before Right Node (only the Root oscillates i.e. Only the Printing of Root node differs i.e. When do we print the Root node, differs)
Specifically, Preorder is Depth First Order Left to Right.