In data structure tree traversal techniques are of three types

1). Inorder Traversal
2). Preorder Traversal
3). Postorder Traversal

In Inorder Traversal left subtree is traversed first in inorder fashion, then root node and at last right sub tree is processed
In Preorder traversal root node is traversed first then left sub tree in inorder fashion and at last right sub tree in inorder fashion
In Post order traversal root is traversed at last first left subtree is traversed, then right subtree and at last root is traversed

Ref: http://gatecrack.org/tree-traversal-techniques-in-data-structure-with-example/