This article discusses the use of Selenium for efficient User Interface (UI) testing automation. It explains what UI testing is, how Selenium stands out in this field, and its working mechanism. The prerequisites and setup process for using Selenium are also detailed. Furthermore, it provides a step-by-step guide on writing the first test script for Selenium UI testing, running tests on Selenium Cloud Grid, and best practices for Selenium UI testing. Lastly, it answers some frequently asked questions about Selenium UI testing.