Button (computing)

In computing, a button is a common metaphor, used in graphical interfaces with a similar objective to that of an ordinary button. Buttons are usually represented as rectangles with a legend or icon inside, generally with a raised effect.

Overview

A typical button is a rectangle or rounded rectangle, wider than it is tall, with a descriptive title in its center. The most common method of pressing a button is to click it with a mouse-controlled pointer, but other inputs, such as keystrokes, can be used to execute a button command. However, a button is not always restricted to a rectangular shape. The only requirement for button interaction is that the user can execute a command via a click action. Thus, images and background areas can be programmed as buttons. When pressed, in addition to performing a predetermined task, buttons often undergo a graphic change to mimic a mechanical button being pressed.

Depending on the circumstance, buttons may be designated to be pressed just once to execute a command, while others may be used to receive instant feedback and may require the user to click more than once to receive the desired result. Other buttons are designed to turn behavior like a check box on and off. These buttons will display a graphical hint (such as staying down after the mouse is released) to indicate the state of the option.

A button often displays a tooltip when a user moves the pointer over it. The tooltip serves as built-in documentation that briefly explains the purpose of the button.

Some very common incarnations of the button widget are:

An OK button to confirm actions and close windows. A Cancel button to cancel actions and close the window. An Apply button to confirm actions without closing the window. A Close button to close windows after changes have been applied

Buttons in the macOS Aqua interface are generally rendered as rounded rectangles of crystallized glass. Normally these buttons are light gray in color and turn blue when pressed. The button with keyboard focus (selectable with the space bar) appears with a blue glow around it. The default button in an active window (selectable with the return key) animates between a bright blue and a darker blue (the same color as a pressed button).

Slightly rounded rectangles with a light gray metallic look are also used, mainly within application toolbars. These buttons appear darker and "pushed in" when pressed.

Window management controls appear in the upper left corner of each window. These buttons are similar in style to the standard aqua buttons, but are color coded as a memory aid. From left to right, these are: "Close window", shown in red; "Minimize window", is shown in yellow; and "Zoom", which is displayed in green, causing the window to resize to better fit its content.

Windows Shell

Buttons in Microsoft Windows are generally rectangular, with slightly rounded corners in Windows XP Vista and 7. In Windows 8 buttons are rectangular with sharp corners. A button with active focus is displayed with a black dotted line just inside the button's border. Also, in newer versions, the default button is displayed with a blue border. In Windows Vista and Windows 7, the default button will slowly fade between its normal appearance and the blue border. The window management controls are in the upper right corner of the application window, and from left to right: "minimize" the window (by making it disappear into the taskbar at the bottom of the screen); maximize the window (causing it to expand to cover the entire screen; if the window is already maximized, the button will restore it to its previous size and position); and close the window.

Linux and other Unix-like systems

The appearance and behavior of buttons on Linux and other Unix-like operating systems are mainly defined by which widget toolkit is being used, the most popular being GTK+ and Qt although other toolkits are used as well. Using multiple tool kits can lead to a less uniform look and feel across applications. Most widget toolkits also have theming capabilities, so there is no single standard look and feel, as there is with Mac OS and Windows.

HTML

Buttons appear as HTML form elements to perform actions such as deleting user input or submitting the form content to the server. Buttons specified in HTML can be rendered by web browsers in different ways, typically using the native button appearance of the underlying operating system, or using a button definition from the browser. Buttons can also be designed by the developer of the website on which the form appears through the use of cascading style sheets.

HTML links are sometimes represented by a graphic that looks a lot like a button. Sometimes this type of link is used in advertisements to induce the user to click on the advertisement and visit the advertiser's site.