Dock

A dock is the operating system’s own strip of application icons, pinned to one edge of the screen and outliving every window on it. Three kinds of thing share the row: launchers a person pinned there deliberately, applications that happen to be running right now, and whatever else the platform lets you drop in (a folder, a file, a minimised window). The strip is the same control in all three cases, which is why a separator usually sits between the pinned section and the temporary one: without it there is no way to see which icons will still be there tomorrow.

The naming is a genuine cross-platform mess and worth learning in full. It is the dock on macOS, iPadOS and most Linux desktops, the taskbar on Windows, and the shelf on ChromeOS. Windows also puts a clock and a notification area in the same strip, which macOS keeps in the menu bar instead, so the two are not quite the same component even though they occupy the same edge. Web and mobile products borrow the shape freely: a bottom navigation bar looks like a dock and is not one, because its items are places inside a single app rather than applications.

Against a toolbar the split is about scope. A toolbar carries commands that act on the document in front of you and dies with that window; a dock switches between applications and belongs to the shell. Against a menu bar it is about shape: a menu bar is a hierarchy of every command an app has, opened one menu at a time, while a dock is a flat row where each icon is one target. An app shell that keeps a persistent left rail of product areas is closer to a dock than to either, and calling it one is fair.

The state a dock has to carry is small but load-bearing: which items are pinned, which are running (conventionally a dot or a line under the icon), and which is frontmost. Launching an app is the moment all of that becomes visible, since an icon can move from launcher to running app without moving position at all. The row’s hover behaviour is a separate term: dock magnification is the bell curve that swells the icons under the pointer, an effect macOS ships turned off, and a strip with it disabled is still very much a dock.