Selenium is an industry-standard open-source testing framework that allows developers to run fast and repeatable tests across all browsers and operating systems, supporting popular scripting languages such as Node.js, Java, Python, PHP, Ruby, or C#. It has evolved from a single browser technology to a standard protocol for human-like interaction with browsers. Selenium 4 is the latest version, using the W3C WebDriver standard protocol, ensuring future-proof support across all browsers. It allows developers and testers to write test scripts in different programming languages that can run on various operating systems and browsers without modification. Selenium enables parallel testing, automates browsers, works across browsers, is up-to-date, runs almost anywhere, and allows customized testing, making it an ideal tool for automated testing.