Bootstrap has become one of the most popular front-end frameworks and open source projects in the world.
The official repository for Bootstrap can be found on Github in twbs / bootstrap.
You can see a live demo example of Bootstrap 3 Theme here: Bootstrap Theme or in this screen shot:
(Sourced from the official repository readme.md)
Within the download you'll find the following directories and files, logically grouping common assets and providing both compiled and minified variations. You'll see something like this:
bootstrap/ ├── css/ │ ├── bootstrap.css │ ├── bootstrap.min.css │ ├── bootstrap-theme.css │ └── bootstrap-theme.min.css ├── js/ │ ├── bootstrap.js │ └── bootstrap.min.js └── fonts/ ├── glyphicons-halflings-regular.eot ├── glyphicons-halflings-regular.svg ├── glyphicons-halflings-regular.ttf └── glyphicons-halflings-regular.woff
Check out the official Bootstrap About Page