Bootstrap is an open-source front-end toolkit created to help designers and developers quickly and efficiently build great stuff online. Its goal is to provide a refined, well-documented, and extensive library of flexible design components created with HTML, CSS, and JavaScript for others to build and innovate on. Today, it has grown to include dozens of components and has become the most popular project on GitHub, with more than 13,000 watchers and 2,000 forks. Mark Otto, the co-creator of Bootstrap, sheds light on how and why Bootstrap was made, the processes used to create it, and how it has grown as a design system.