Containers are a fundamental building block of Bootstrap that contain, pad, and align your content within a given device or viewport.
Containers are the most basic layout element in Bootstrap and are required when using default grid system. Containers are used to contain, pad, and (sometimes) center the content within them.
Bootstrap comes with three different containers:
The default container .container class is a responsive, fixed-width container, meaning its max-width changes at each breakpoint.
<!-- Content here -->
Responsive containers allow to specify a class that is 100% wide until the specified breakpoint is reached. For example, .container-md is 100% wide to start until the md breakpoint is reached, where it will scale up with lg, xl, and xxl.
Use .container-fluid for a full width container, spanning the entire width of the viewport.