A throbber is a graphic found in a graphical user interface

Graphical user interface

In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...

 of a computer program

Computer program

A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...

 (especially a web browser

Web browser

A web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier and may be a web page, image, video, or other piece of content...

) that animates

Animation

Animation is the rapid display of a sequence of images of 2-D or 3-D artwork or model positions in order to create an illusion of movement. The effect is an optical illusion of motion due to the phenomenon of persistence of vision, and can be created and demonstrated in several ways...

 to show the user that the program is performing an action (such as downloading a web page).

Typical characteristics

Usually the throbber is found on the right side of a program's toolbar

Toolbar

In a graphical user interface, on a computer monitor, a toolbar is a GUI widget on which on-screen buttons, icons, menus, or other input or output elements are placed. Toolbars are seen in office suites, graphics editors, and web browsers...

 or menu bar

Menu bar

A menu bar is a region of a screen or application interface where drop down menus are displayed. The menu bar's purpose is to supply a common housing for window- or application-specific menus which provide access to such functions as opening files, interacting with an application, or displaying...

. The form the throbber takes varies, but it is common for it to be the logo

Logo

A logo is a graphic mark or emblem commonly used by commercial enterprises, organizations and even individuals to aid and promote instant public recognition...

 of the program it is part of. Most of the time the throbber is a still image (known as its resting frame), but when the program is performing an action the throbber begins to animate in a loop to let the user know that the program is busy and has not frozen

Hang (computing)

In computing, a hang or freeze occurs when either a single computer program, or the whole system ceases to respond to inputs. In the most commonly encountered scenario, a workstation with a graphical user interface, all windows belonging to the frozen program become static, and though the mouse...

. Once the action is complete, the throbber returns to its resting frame. Normally, it is possible for the user to continue interacting with the program while the throbber is animating (one such possibility may be to press a stop button to cancel the action that the program is doing). Often, clicking on the throbber itself will go to the program's website

Website

A website, also written as Web site, web site, or simply site, is a collection of related web pages containing images, videos or other digital assets. A website is hosted on at least one web server, accessible via a network such as the Internet or a private local area network through an Internet...

.

History

One of the early (if not the earliest) uses of a throbber was in the NCSA Mosaic web browser of the early 1990s, which featured an NCSA

National Center for Supercomputing Applications

The National Center for Supercomputing Applications is an American state-federal partnership to develop and deploy national-scale cyberinfrastructure that advances science and engineering. NCSA operates as a unit of the University of Illinois at Urbana-Champaign but it provides high-performance...

 logo that animated when Mosaic was downloading a web page. As the user could still interact with the program, the mouse pointer remained normal (and not a busy symbol, such as an hourglass); therefore, the throbber provided a visual indication that the program was performing an action. Clicking on the throbber would stop the page loading; later web browsers added a separate Stop button for this purpose. An Easter egg

Easter egg (media)

Image:Carl Oswald Rostosky - Zwei Kaninchen und ein Igel 1861.jpg|250px|thumb|right|Example of Easter egg hidden within imagerect 467 383 539 434 desc none...

 was implemented that replaces the throbber with an image of the rotating head of Tom Magliery when browsing his home page. This Easter egg appears with any web site whose URL contains the substring "~mag/".

Netscape

Netscape

Netscape Communications is a US computer services company, best known for Netscape Navigator, its web browser. When it was an independent company, its headquarters were in Mountain View, California...

, which soon overtook Mosaic as the market-leading web browser, also featured a throbber. In version 1.0 of Netscape, this took the form of a big blue "N" (Netscape's logo at the time). The animation depicted the "N" expanding and contracting, thus explaining why these animations became known as throbbers. When Netscape unveiled its new logo (a different "N" on top of a hill), they held a competition to find an animation for it. The winning design (featuring the new-look "N" in a meteor shower

Meteor shower

A meteor shower is a celestial event in which a number of meteors are observed to radiate from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extremely high speeds on parallel trajectories. Most meteors are smaller...

) became very well known and almost became an unofficial symbol of the World Wide Web

World Wide Web

The World Wide Web is a system of interlinked hypertext documents accessed via the Internet...

. Later, Internet Explorer

Internet Explorer

Windows Internet Explorer is a series of graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems, starting in 1995. It was first released as part of the add-on package Plus! for Windows 95 that year...

's blue "e" enjoyed similar status, though it was only used as a throbber in early versions of the browser.

The IBM WebExplorer offered a webpage the opportunity to change the look and the animation of the throbber by using a proprietary HTML code. The use of web frames, a feature introduced later, leads WebExplorer to confusion on modern pages due to the way this feature was implemented.

The Arena

Arena (web browser)

The Arena browser was an early testbed web browser and web authoring tool for Unix. Originally authored by Dave Raggett in 1993, the browser continued its development at CERN and the World Wide Web Consortium and subsequently by Yggdrasil Computing...

 web browser has a command line option to change the throbber with a local file.

Initially, throbbers tended to be quite large, but they reduced in size along with the size of toolbar buttons as graphical user interfaces developed. Their usefulness declined somewhat as most operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

s introduced a different mouse-pointer icon to indicate "working in background", and they are no longer included in all web browsers (Opera

Opera (web browser)

Opera is a web browser and Internet suite developed by Opera Software with over 200 million users worldwide. The browser handles common Internet-related tasks such as displaying web sites, sending and receiving e-mail messages, managing contacts, chatting on IRC, downloading files via BitTorrent,...

 currently does not use one, for example). Furthermore, even web browsers that do use them, such as Mozilla Firefox

Mozilla Firefox

Mozilla Firefox is a free and open source web browser descended from the Mozilla Application Suite and managed by Mozilla Corporation. , Firefox is the second most widely used browser, with approximately 25% of worldwide usage share of web browsers...

, depict images less elaborate than their predecessors.

Often browsers shipped with ISP

Internet service provider

An Internet service provider is a company that provides access to the Internet. Access ISPs directly connect customers to the Internet using copper wires, wireless or fiber-optic connections. Hosting ISPs lease server space for smaller businesses and host other people servers...

 CDs, or those customized according to co-branding

Co-branding

Co-branding refers to several different marketing arrangements:Co-branding, also called brand partnership, is when two companies form an alliance to work together, creating marketing synergy...

 agreements, have a custom throbber. For example the version of Internet Explorer included with AOL

AOL

AOL Inc. is an American global Internet services and media company. AOL is headquartered at 770 Broadway in New York. Founded in 1983 as Control Video Corporation, it has franchised its services to companies in several nations around the world or set up international versions of its services...

 disks has an AOL throbber instead of the standard "e".

Spinning wheel

Throbbers saw a resurgence with client side applications (such as Ajax

Ajax (programming)

Ajax is a group of interrelated web development methods used on the client-side to create asynchronous web applications...

 Web applications) where an application within the web browser would wait for some operation to complete. Most of these throbbers were known as a "spinning wheel", which typically consist of 8, 10, or 12 part-radial lines or discs arranged in a circle, as if on a clock face

Clock face

A clock face is the part of an analog clock that displays the time through the use of a fixed numbered dial or dials and moving hands. In its most basic form, recognized universally throughout the world, the dial is numbered 1–12 indicating the hours in a 12-hour cycle, and a short hour hand...

, highlighted in turn as if a wave is moving clockwise around the circle.

In text user interface

Text user interface

TUI short for: Text User Interface or Textual User Interface , is a retronym that was coined sometime after the invention of graphical user interfaces, to distinguish them from text-based user interfaces...

s, the spinning wheel is commonly replaced by a spinning bar, a fixed-width character which is cycled between |/-\ forms in order to create an animation effect. Unlike graphical activity indicators, the spinning bar is commonly combined with progress displays, since the lower resolution of character-based progress bars requires a separate indication of activity. This use dates from early versions of the UNIX operating system and DR DOS utilities in the 1980s.