In this tutorial, we learn how to build a multimodal WhatsApp bot using PHP, Twilio, and Google Gemini's API. The final output will be a WhatsApp bot that can respond to text, image, and audio input. We first retrieve the necessary credentials for building our application and store them in an .env file. Then, we create functions to send requests to Gemini's API and handle incoming messages on Twilio. Finally, we test the application by sending different types of inputs to the bot and observe its responses. The code used in this tutorial can be found in a GitHub repository.