A Bootstrap Navbar is a navigation header that is commonly used to display branding and navigation options.
The Bootstrap Navbar can be expanded responsively at any breakpoint using the utility class navbar-expand-{bp}
.
The below image shows a Navbar displayed on a large screen.

The below image shows a Navbar displayed on a small screen.

You can find how to build a Bootstrap Navbar here.
Starter App 104 includes header, a Component that uses the Bootstrap Navbar.