Anatomy
The desktop browser layout is essentially broken up into two sections. All of the UI that frame and show up around the web content is referred to as "the chrome" (tab strip, toolbar, bookmarks toolbar, infobar, sidebar, find bar, etc.) and the UI populated within the web content window is referred to as "in-content."

Firefox for macOS
Key |
Color |
Description |
---|---|---|
1 |
Yellow |
The chrome |
2 |
Purple |
In-content |