# What is Utility Class?

A single CSS class that does exactly one thing, like `font-bold`, `mt-4`, or `flex`. You combine many utility classes to build a full style without writing custom CSS.

## In real work

Use only utility classes. No wrapper classes or custom CSS. Compose layout with flex, gap, and padding utilities.

## Related terms

- [Component Library](https://prompthausapp.com/learn/component-library.md)
- [Design System](https://prompthausapp.com/learn/design-system.md)
- [shadcn](https://prompthausapp.com/learn/shadcn.md)
- [Ant Design](https://prompthausapp.com/learn/ant-design.md)
- [Radix UI](https://prompthausapp.com/learn/radix-ui.md)

## How is this different from Googling it?

Google gives a definition. Prompthaus pairs each term with how it shows up in standups, PRs, prompts, and design reviews—then quizzes you until the word sticks. One term a day on iPhone.

- Category: UI Kits
- HTML: https://prompthausapp.com/learn/utility-class
- App Store: https://apps.apple.com/us/app/prompthaus-ai-vocabulary/id6776314407