Which programming language is commonly used to create interactive effects within web browsers?

JavaScript is the programming language commonly used to create interactive effects within web browsers. It is designed specifically for this purpose and allows developers to implement dynamic features on websites, such as form validation, animations, interactive maps, and real-time content updates. JavaScript runs directly in the browser, enabling it to respond to user actions without needing to reload the entire web page. This capability fundamentally enhances the user experience by making web applications more engaging and responsive.

Other programming languages mentioned, such as Python, C++, and Ruby, have their own specific uses but are not typically used for client-side scripting in web browsers. Python is frequently utilized for server-side applications, data analysis, and machine learning. C++ is more commonly used for system programming and applications requiring high performance. Ruby is often used in web development through frameworks like Ruby on Rails, but it does not run natively in web browsers for client-side interactivity like JavaScript does.