What is the difference between bootstrap.css and bootstrap-theme.css?

Question

What is the difference between bootstrap.css and bootstrap-theme.css found in the bootstrap file when we download bootstrap?

Answer 1

bootstrap.css is the core css for BootStrap that defines all the style for various controls/components, where as bootstrap-theme.css defines the themes (gradient/animation) for buttons,dropdown menu,navbar,progressbar,panels.

Most of the times adding bootstrap.css is enough for bootstrap to work, but for gradient/animation, you can use bootstrap-theme.css.

You can see the difference on http://getbootstrap.com/css/#buttons and then click on Preview theme from the affix menu (fixed menu on right side)