Tailwind CSS is a utility-first CSS framework that allows developers to create custom designs without having to leave their HTML. It provides a set of pre-defined classes that can be combined to build responsive and modern user interfaces quickly and efficiently. Unlike traditional CSS frameworks that offer predefined components, Tailwind CSS encourages a more flexible approach. Developers can easily customize styles by composing utility classes, leading to a more streamlined workflow and a unique design tailored to specific project needs.