Responsive frontend website development involves designing and coding a website in such a way that it adapts and responds to different screen sizes and devices. This means that the website will look and function well on a desktop computer, laptop, tablet, or mobile phone.

To achieve this, a frontend developer typically uses HTML, CSS, and JavaScript to create the website's user interface and functionality. They may also use frameworks and libraries such as Bootstrap, jQuery, or React to streamline the development process and ensure cross-browser compatibility.

In addition to creating a visually appealing and functional website, a frontend developer must also ensure that the website is accessible to all users, including those with disabilities. This involves adhering to web accessibility guidelines such as WCAG 2.1 and implementing features such as keyboard navigation and alternative text for images.

Overall, responsive frontend website development is a complex and ongoing process that requires a strong understanding of web technologies, design principles, and user experience.