The popular coding language often used for web development alongside HTML and CSS is JavaScript. JavaScript is a versatile programming language that enables dynamic content creation, interactivity, and enhanced user experiences on websites. It allows developers to implement complex features like animations, form validations, and responsive interfaces. Being a client-side language, JavaScript executes in the user's browser, thereby reducing server load. Its widespread adoption and robust ecosystem make it essential for modern web development, complementing both HTML and CSS in building comprehensive web applications.