diff --git a/README.md b/README.md
index 10bfee0..cc3ec6c 100644
--- a/README.md
+++ b/README.md
@@ -3,8 +3,12 @@ A very simple and naive android app to calculate 1 kilogram/liter price using ca
 
 ### APK for Android
 - Open https://github.com/randaller/kiloprice/actions/
-- Click on the latest action run on the top
-- Scroll down to Artifacts and download app-release.zip with apk file
+- Click on the latest action run on the top of runs list
+- Scroll down to Artifacts and download app-release.zip with apk file built by GitHub
+
+### Principles of work
+The application works completely offline, no internet access needed. The only camera access permission is required.
+Application uses Google AI internal tools on your phone, does OCR of price tag, and naively assume what is volume/weight and price.
 
 ### Screenshots
 ![Better than 1000 words](https://github.com/randaller/kiloprice/raw/main/static/67580595-15b8-48fa-8fdc-f1a6addd7925.jpg)