Tailwind CSS is an open-source CSS framework. Unlike other frameworks, like Bootstrap, it does not provide a series of predefined classes for elements such as buttons or tables. Instead, it creates a list of "utility" CSS classes that can be used to style each element by mixing and matching.
For example, in other traditional systems, there would be a class message-warning that would apply a yellow background color and bold text. To achieve this result in Tailwind, one would have to apply a set of classes created by the library: bg-yellow-300 and font-bold.
As of 5 August 2024, Tailwind CSS has over 81,000 stars on GitHub.