It is the most popular project on GitHub.
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.
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.