Bootstrap
Originally by Twitter
Bootstrap is a popular open-source CSS framework that provides a responsive grid system, prebuilt UI components, and utility classes for building mobile-first web interfaces quickly.
Definition
Bootstrap is a popular open-source CSS framework that provides a responsive grid system, prebuilt UI components, and utility classes for building mobile-first web interfaces quickly.
Overview
Bootstrap was created by Twitter engineers Mark Otto and Jacob Thornton, released in 2011, and became one of the most widely used front-end frameworks on the web. Its 12-column responsive grid system and library of prebuilt components — navigation bars, modals, forms, buttons, cards — let developers assemble consistent, mobile-friendly layouts quickly, styled through Sass variables for easy theming. The framework evolved significantly across major versions: Bootstrap 2 and 3 embraced a mobile-first, responsive approach as smartphone usage grew, Bootstrap 4 moved its grid system to flexbox, and Bootstrap 5 removed the jQuery dependency entirely, relying on vanilla JavaScript for its interactive components. Today it's commonly compared with utility-first alternatives like Tailwind CSS, and both are frequently used inside component-based frameworks such as React or Vue.js.
Key Features
- Responsive 12-column grid system
- Extensive library of prebuilt UI components
- Sass-based variables and theming system
- No jQuery dependency since version 5
- Utility classes for spacing, typography, and layout
- Accessibility-conscious component defaults
- Broad cross-browser support
- Large ecosystem of free and paid themes