Bootstrap

About Bootstrap

Bootstrap is an open-source frontend toolkit for building responsive websites and web applications with HTML, CSS, and JavaScript. It provides a prebuilt grid system, a library of UI components, and a set of JavaScript plugins (such as modals, dropdowns, popovers, tooltips, and offcanvas menus) that work without requiring jQuery. Plugins can be controlled through HTML data attributes or invoked programmatically in JavaScript.

The library is built with Sass, allowing developers to import only the components they need, override variables, and configure global options such as gradients and shadows. Bootstrap 5 also exposes its theme, component, and utility styles as CSS variables that can be overridden directly in custom CSS without rewriting whole rule sets. Its utility classes are generated through a configurable Sass-based Utility API, which lets developers add, remove, or modify utilities such as spacing, color, and sizing classes, and make them responsive or state-variant.

Bootstrap can be installed via npm, RubyGems, Composer, or Meteor, or included directly through a CDN for compiled CSS and JS files. It is intended for developers building or customizing responsive web interfaces, from those who want a ready-made design system to those who want to extend or theme it through Sass and CSS variables.

Key features

• Responsive grid system and prebuilt CSS components
• Sass-based architecture for modular customization
• Utility API for generating and customizing utility classes
• CSS variables for theming at root, component, and utility levels
• JavaScript plugins (modals, dropdowns, tooltips, offcanvas) that work without jQuery

Frequently asked questions