Muting and unmuting in video calling apps is crucial for user experience. The Twilio Programmable Video App with React.js allows developers to add this functionality, enabling users to mute or unmute their audio or video tracks. By using the Twilio CLI, a free account, and Node.js v10+, developers can configure their backend and frontend to work together seamlessly. The AVControl component is used to manage the different icons that represent the on/off state of each track, while the Track component handles the actual muting and unmutting process. With this setup, users can see their own mute/unmute icons and control their audio or video tracks accordingly. This tutorial provides a step-by-step guide for developers to implement muting and unmuting in their React video chat apps using Twilio Programmable Video.