User Interface (UI) testing is an essential process in web development that ensures the interface of a web application is both functional and intuitive for users, impacting their overall experience and satisfaction. This type of testing examines the visual and interactive elements that users engage with, such as buttons, text fields, and dropdown menus, to identify any defects that could impair user behavior or fail to meet specifications. UI testing can be conducted manually or through automation, with automation offering advantages in terms of speed, accuracy, and the ability to handle complex websites. Selenium is a popular tool for automating these tests, providing benefits like reduced human error and efficient cross-browser testing to ensure compatibility across different browsers. Techniques such as exploratory testing, scripted testing, and user experience testing are employed to assess website performance, while tools like LambdaTest and Katalon Studio facilitate efficient testing processes. The ultimate goal of UI testing is to enhance the user experience by ensuring all elements function as intended, thereby providing a seamless and engaging interface that can help a website stand out in a competitive market.