diff --git a/README.md b/README.md
index 8a08b7b..577b460 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,3 @@
-# nl
+# Num Lines tool from Learn Haskell By Example
+
+[Book](https://www.manning.com/books/learn-haskell-by-example)