Which of the following is a common programming language used for web development?

JavaScript is a fundamental programming language widely used in web development, particularly for creating interactive and dynamic content on websites. It operates primarily on the client side within the user's web browser, allowing developers to manipulate elements in real-time without needing to reload the page. This capability facilitates a more engaging user experience, making JavaScript indispensable in modern web applications.

It is known for its versatility and compatibility with various web technologies. When paired with HTML and CSS, JavaScript forms the core trio for web development. Furthermore, JavaScript can be used in server-side programming through environments like Node.js, extending its functionality beyond just the front end. Overall, its significance in web development is unparalleled, which is why it stands out as the correct answer in this context.