This tutorial is about building a wireless lock system that can be controlled remotely using SMS messages. The system uses an Arduino Uno, a servo motor, and Node.js to communicate with the Twilio API. The user will need to install the necessary software and hardware components, including the Arduino IDE, Node.js, and a serial port connection. The system will allow users to lock and unlock their deadbolt door via SMS messages, using a unique verification code. The tutorial also covers setting up a publicly accessible web URL for Twilio to POST incoming text messages, using ngrok.