Intern is a modern, flexible, open source JavaScript testing stack that supports the full testing lifecycle and multiple environments for testing in browsers, Node.js, and in the cloud. It provides features such as code coverage, CI integration, and visual performance regression testing. With recent support from the Mozilla MOSS program, Intern has added capabilities for performance benchmarking, accessibility testing, and visual regression testing. To get started with visual regression testing using Intern and Sauce Labs, you need to create a test config and tests using the intern-cli tool, install the `intern-visual` plugin, and configure it as a package with your module loader. Visual regression tests can be written programmatically or via configuration and provide a quick way to establish baselines for how an application should appear. The `intern-visual` plugin provides tools such as visual test reporters and command helpers that accept screenshots as parameters. The plugin also generates HTML reports showing any visual regressions, allowing developers to quickly identify changes in the application's appearance. With its open source nature and extensive feature set, Intern is a popular choice for developers looking to automate their testing workflows.