diff --git a/README.md b/README.md
index 414dd66..6f503e6 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,7 @@
 wbackup
 ===============
+
+Calclate 32bit checksum and SHA256 hash.
+this file exist in duplicate check database.
+if not exist then comppress source file and export binary database.
+add sourcefile database.