diff --git a/merkle/doc.go b/merkle/doc.go
new file mode 100644
index 000000000..da65dd858
--- /dev/null
+++ b/merkle/doc.go
@@ -0,0 +1,31 @@
+/*
+Package merkle computes a deterministic minimal height Merkle tree hash.
+If the number of items is not a power of two, some leaves
+will be at different levels. Tries to keep both sides of
+the tree the same size, but the left may be one greater.
+
+Use this for short deterministic trees, such as the validator list.
+For larger datasets, use IAVLTree.
+
+Be aware that the current implementation by itself does not prevent
+second pre-image attacks. Hence, use this library with caution.
+Otherwise you might run into similar issues as, e.g., in early Bitcoin:
+https://bitcointalk.org/?topic=102395
+
+                        *
+                       / \
+                     /     \
+                   /         \
+                 /             \
+                *               *
+               / \             / \
+              /   \           /   \
+             /     \         /     \
+            *       *       *       h6
+           / \     / \     / \
+          h0  h1  h2  h3  h4  h5
+
+TODO(ismail): add 2nd pre-image protection or clarify further on how we use this and why this secure.
+
+*/
+package merkle
\ No newline at end of file