I was reading the Bootstrap Getting Started docs, and I came across Pre-Compiled Source as a feature. Upon downloading the package, I just found .js, .css, and some image files. What is there to be pre-compiled? Doesn't it all compile in the browser upon page load? I'm guessing this means that it was compiled and tested before shipping, but I don't understand why this would need to be advertised. 
What does it mean for Bootstrap to be precompiled?
web development;web applications
Bootstrap uses LESS files to generate CSS files. The pre-compiled version contains the output from LESS. If you want to modify Bootstrap you'll need the source and then compile the LESS files into CSS.The term compile is the word LESS uses on their website.http://lesscss.org/Doesn't it all compile in the browser upon page load? I'm guessing this means that it was compiled and tested before shipping, but I don't understand why this would need to be advertised.No, Bootstrap can not run in the browser without the CSS being compiled using LESS.