Selenium Grid has been rewritten from scratch with modern infrastructure advantages such as Docker and distributed tracing. It allows users to run tests in parallel by distributing them across different hosts, specifying different operating systems and browsers. The new version provides a feature that enables relaying commands to a service that supports WebDriver, allowing users to access capabilities and see test results on Sauce Labs. To get started with Selenium Grid 4, users can follow the official documentation from the Selenium project or extend their local instance to access Sauce Labs capabilities. The best way to learn about the new features is by checking out the Appium Conference 2021 talk or following the blog post written by Selenium Project lead Simon Stewart.