The MediaRecorder API is an HTML5 feature that allows web developers to record and save audio or video from users' devices directly in a web browser. To start with the MediaRecorder API, you need a MediaStream, which can be obtained by getting access to a user's camera, microphone, or desktop. The MediaRecorder object initializes with the media stream and an options object, including the MIME type of the recording. The recorder emits events for various reasons, such as when it starts or stops recording, pauses, resumes, or is completed. The most important event is the dataavailable event, which contains a chunk of the recorded audio. By listening to this event, you can collect chunks and then gather them into a Blob object once the recording is complete. The MediaRecorder API has various applications, including real-time video chat over WebRTC, recording audio or video from users directly in a web browser, and playing back recordings using an <audio> element. While it doesn't support saving recordings to the desktop yet, its potential uses are vast, and developers can explore alternatives like IndexedDB or sending recordings to a server.