Bar

What is a "Bar" in the Computer?

A bar is a narrow horizontal or vertical rectangle on the screen that indicates some sort of information or contains widgets that you can interact with. The term "bar" is common because many widgets or sections of widgets in a graphical user interface fill the whole horizontal or vertical space of their containers. Some examples of bars include:

• The task bar of the operating system.
• The title bar of a window.
• The menu bar of a window.
• The tool bars of a window.
• The status bar of a window.
• The scroll bars of a window.
• The header bar of a window.
• The address bar of applications that can navigate from one location to another.
• The progress bar of a task, such as a download.

The term bar seems to be used only with narrow stripes. Rectangles that can be more square-looking tend to get other terms, such as toolbox and ribbon.

Spelling

Many terms from this concept have two spellings, as a phrase (task bar, title bar, menu bar, status bar, scroll bar), and a single-word portmanteau (taskbar, titlebar, menubar, statusbar, scrollbar).

It's possible that one reason for this is due to how they're spelled in programming languages. Most programming languages do not allow spaces in the middle of names, so even "progress bar" would be spelled ProgressBar in code. When programmers talk about these widgets, they may spell their names the way it's spelled in the code they wrote, leading to these spellings becoming accepted among computer users.