Glossary » modal
a type of interface where the user moves between different states, or modes. In each mode, input from the user is interpreted in a different way. When a user is in a given mode, it’s a good idea to provide an extremely salient indicator of which mode is currently active, e.g. by providing a large icon or shifting the color of the screen.
Modes are usually good to avoid because users are restricted in their available actions and they may be confused that the meaning of their actions changes as they change contexts. However, modes can sometimes be helpful to control and guide input (providing security and preventing accidental errors), and modes may be appropriate when they are short and actively maintained by a user (e.g. the fact that keys refer to capital letters only when the Shift key is held down) and when they follow well-understood conventions, such as painting tools.
Examples of modes include:
- Choosing a painting tool in a paint program. When the Line tool is selected, for instance, all mouse clicks create lines. When a brush tool is selected, the user is in a different mode because all mouse clicks are then interpreted as painting.
- Old text processors, such as ‘vi’ in UNIX, often used a command mode and an edit mode. In a command mode, keystrokes issued commands. In an edit mode, keystrokes were entered into a text document.
- Moving between pages on a website. Each page is a mode which limits the kinds of actions a user can take (where they can go).
- Modal dialog boxes are ones that force a user to respond to them before the user can go back to using other aspects of the application.