Athrobber, also known as aloading icon, is ananimatedgraphical control element used to show that acomputer program is performing an action in the background (such as downloading content, conducting intensive calculations or communicating with an external device).[1][2][3] In contrast to aprogress bar, a throbber does not indicate how much of the action has been completed.
An early use of a throbber occurred in theNCSA Mosaic web browser of the early 1990s, which featured anNCSA logo that animated while Mosaic downloaded a web page. As the user could still interact with the program, thepointer 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.
TheNetscape 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 – hence the name "throbber".[4]
TheIBM WebExplorer offered awebpage the opportunity to change the look and the animation of the throbber by using proprietaryHTML code.[5]
TheArena web browser has acommand-line option to change the throbber with a local file.[6]
.gif)
Throbbers also appear inclient side applications (such asAjaxweb apps) where an application within the web browser would wait for some operation to complete. Most of these throbbers appear as a "spinning wheel", which typically consist of 8, 10, or 12 part-radial lines or discs arranged in a circle, as if on aclock face, highlighted in turn as if a wave is moving clockwise around the circle.
Intext user interfaces andcommand lines, the spinning wheel is commonly replaced by afixed-width character which is cycled through discrete states, such as "|", "/", "-" and "\", which act as the frames of a looping animation-like effect. Unlike graphical activity indicators, this style of throbber is commonly paired with a progress display like a bar, since the lower effective resolution of character-based progress bars can benefit from a separate indication of activity. Often, the spinner is displayed at or near the position of thetyping cursor, then called a "spinning cursor" or "rotating cursor". This style of throbber dates from versions ofUNIX appearing in the latter 1970s, andDR-DOS utilities in the 1980s, since it requires at least acharacter-cell addressable display—i.e. one which can be updated quickly to make precise changes to already displayed text—but given that is otherwise simple to program.
Animated icons that are used to replace the "meteor shower" icon in Netscape Navigator. Taken from the nickname given to the original Netscape logo, which appeared to throb during document transfers. New icons, such as the J. R. "Bob" Dobbs throbber, are currently traded over the Net.
Netscape, which soon overtook Mosaic as the market-leading web browser, 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 – hence the name "throbber" (now you know!!). 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) became very well-known and almost became an unofficial symbol of the World Wide Web Later. Internet Explorer's blue "e" enjoyed similar status, though it only functioned as a throbber in early versions of the browser.