Puppeteer is a powerful Node.js library that enables Chrome browser testing, allowing developers to automate web application testing with ease. It introduces the concept of headless browsers, which are faster, more flexible, and stable under automation stress. Puppeteer simplifies automated tasks on browsers by providing an API control over Chrome's DevTools Protocol, making it easier to test UI regression, screenshots, performance, load testing, and end-to-end testing. Its simplicity and flexibility have made it a popular choice among developers, and its integration with other tools like Jest, Headless Chrome, and LambdaTest has further enhanced its capabilities. With Puppeteer, developers can exercise control over the browser and website response time, test caching, and measure performance metrics to optimize websites for different devices and network speeds.