[MrJohz]

Component in this sense is typically just "a composable unit of UI". That often corresponds well with JS frameworks that want to be able to attach state and behaviour to those units, but you can have components without needing Javascript.

For example, partials in classic server-side rendering libraries can be thought of as components, although they tend not be used at such small scales. In CSS patterns like BEM, the B ("Block") is in many ways a component with different sub-elements and states. This is partly why Tailwind provides the @apply directive - it allows you to create "CSS only" components even if you don't have other ways of creating components. That said, other forms of components are often easier to use, and if you already are using them, Tailwind recommends using them for style reuse rather than @apply.