Overlays & Surfaces · Containers
Panel
also known as pane
A panel is a bounded area within a layout that holds a coherent set of content or tools, often persistent, such as a sidebar, properties panel, or preview pane. Panels are part of the app's structure rather than temporary overlays. They can be fixed, collapsible, or dockable.
See it live — shadcn/ui · MUI · Ant Design
Don't confuse it with
A panel is a durable structural region of the layout; a drawer or side sheet slides in and out on demand. Compared with a card, a panel is larger and holds tools or a working area rather than one summarized item.
In the wild
The layers panel on the left side of Photoshop is a panel.