Bootstrap was developed by Mark Otto and Jacob Thornton at Twitter as a framework to encourage consistency across internal tools. Before Bootstrap, various libraries were used for interface development, which led to inconsistencies and a high maintenance burden. According to Twitter developer Mark Otto, in the face of those challenges:
"...super small group of developers and I got together to design and build a new internal tool and saw an opportunity to do something more. Through that process, we saw ourselves build something much more substantial than another internal tool. Months later, we ended up with an early version of Bootstrap as a way to document and share common design patterns and assets within the company.
The first deployment under real conditions happened during Twitter's first Hackweek. Mark Otto showed some colleagues how to accelerate their project's development with the help of the toolkit. As a result, dozens of teams have moved to the framework.
In August, 2011 Twitter released Bootstrap as open-source. In February 2012, it was the most popular GitHub development project.
Bootstrap has relatively incomplete support for HTML5 and CSS 3, but it is compatible with all major browsers. Basic information of compatibility of websites or applications is available for all devices and browsers. There is a concept of partial compatibility that makes the basic information of a website available for all devices and browsers. For example, the properties introduced in CSS3 for rounded corners, gradients and shadows are used by Bootstrap despite lack of support by older web browsers. These extend the functionality of the toolkit, but are not required for its use.
Since version 2.0 it also supports responsive design. This means the layout of web pages adjusts dynamically, taking into account the characteristics of the device used (PC, tablet, mobile phone).
Bootstrap is open source and available on GitHub. Developers are encouraged to participate in the project and make their own contributions to the platform.