The programming language often associated with web development alongside HTML and CSS is JavaScript. This dynamic language enhances user interactions on websites, enabling features such as interactive elements, animations, and real-time updates. JavaScript runs in the web browser, allowing developers to build responsive applications that can process user inputs without waiting for server responses. Additionally, JavaScript frameworks like React, Angular, and Vue.js have gained popularity for building scalable and organized web applications. Its ubiquity and versatility make it an essential skill for modern web developers.