Bootstrap/docs/layout/containers.md

layout	title
page	Containers

Bootstrap requires a containing element to wrap site contents and house our grid system. You may choose from one of two containers—fixed width or fluid width—to use in your projects.

Containers can be nested, but be aware that most layouts don't require it.

Use .container for a responsive fixed width container. This will center content withing the viewport and apply the appropriate width for a given device size.

{% highlight html %}

...

{% endhighlight %}

Use .container-fluid for a full width container, spanning the entire width of the viewport.

{% highlight html %}

...

{% endhighlight %}