diff --git a/graphs_trees/bst/bst.py b/graphs_trees/bst/bst.py
index 9b23e8e2..ea84f684 100644
--- a/graphs_trees/bst/bst.py
+++ b/graphs_trees/bst/bst.py
@@ -1,3 +1,9 @@
+#coding question using bst
+#Binary Search Tree is a node-based binary tree data structure which has the following properties:
+#The left subtree of a node contains only nodes with keys lesser than the node’s key.
+#The right subtree of a node contains only nodes with keys greater than the node’s key.
+#The left and right subtree each must also be a binary search tree.
+
 class Node(object):
 
     def __init__(self, data):
@@ -40,4 +46,4 @@ def _insert(self, node, data):
                 node.right.parent = node
                 return node.right
             else:
-                return self._insert(node.right, data)
\ No newline at end of file
+                return self._insert(node.right, data)
diff --git a/sorting_searching/merge_sort/test_merge_sort.py b/sorting_searching/merge_sort/test_merge_sort.py
index e1d8fd9e..47daca56 100644
--- a/sorting_searching/merge_sort/test_merge_sort.py
+++ b/sorting_searching/merge_sort/test_merge_sort.py
@@ -1,3 +1,6 @@
+#Like QuickSort, Merge Sort is a Divide and Conquer algorithm.
+#It divides input array in two halves, calls itself for the two halves and then merges the two sorted halves.
+
 from nose.tools import assert_equal, assert_raises
 
 
@@ -28,4 +31,4 @@ def main():
 
 
 if __name__ == '__main__':
-    main()
\ No newline at end of file
+    main()