styled-components is a React-focused CSS-in-JS library that enables developers to style applications by writing real CSS directly inside JavaScript using tagged template literals. Instead of separating styles into external CSS files, styles are co-located with components, meaning each React component can encapsulate its own styling logic.

The library generates unique class names for each styled component and injects only the styles that are actually used on the page. This approach helps prevent style conflicts, improves maintainability, and simplifies component-based UI development.

styled-components also supports dynamic styling based on component props and themes, allowing styles to change in response to application state without manual class management. It integrates deeply with React rendering and supports modern features like server-side rendering, theming systems, and React Server Components.

It is widely used in design systems and large-scale React applications where component encapsulation, maintainability, and predictable styling behavior are important. The library aims to improve developer experience by bringing CSS closer to component logic while preserving full CSS capability.

Key features include:

• CSS-in-JS styling using tagged template literals
• Scoped, automatically generated class names to prevent conflicts
• Dynamic styling based on props and themes
• Full support for standard CSS features (nesting, pseudo-selectors, media queries)
• Server-side rendering and React integration support

Common use cases include:

• Building React component libraries
• Implementing design systems
• Managing scoped styles in large applications
• Creating themeable UI components
• Replacing traditional CSS or preprocessor workflows in React projects

styled-components is an open-source project created by Max Stoiber and Glen Maddern and maintained by a community of contributors.