Bootstrap is a free and open-source collection of CSS and JavaScript/jQuery code used for creating dynamic websites layout and web applications

Bootstrap, as defined on its website, is "the world's most popular open-source front-end toolkit, featuring Sass variables and mixins, a responsive grid system, extensive prebuilt components, and powerful plugins."

Bootstrap is one of the most popular CSS libraries. It allows developers to easily use beautiful styles and components and create responsive websites. Using Bootstrap can save developers time, especially with components that are used in almost every project.

the newest version of Bootstrap, which is the most popular HTML, CSS, and JavaScript framework for creating responsive, mobile-first websites.

Bootstrap is one of the most popular front-end frameworks which has really a nice set of predefined CSS codes. Bootstrap uses different types of classes to make responsive websites.

Bootstrap is a framework that is suitable for mobile-friendly web development. it means the code and the template available on bootstrap are applicable to various screen sizes. It is responsive for every screen size.