The programming language mostly associated with web-based applications is JavaScript. It plays a crucial role in creating interactive and dynamic web pages, making it an essential component alongside HTML and CSS. JavaScript allows developers to implement features such as form validation, animations, and real-time updates without requiring page reloads. Moreover, frameworks and libraries built on JavaScript, such as Node.js for server-side development and jQuery for simplifying DOM manipulation, further enhance its capabilities. Its wide adoption and compatibility with various technologies make it a cornerstone of modern web development.