Google has had many logos since its renaming from BackRub. The first logo was created by Sergey Brin using GIMP, but the current official Google logo was designed by Ruth Kedar, and is a wordmark based on the Catull typeface, an old style serif typeface designed by Gustav Jaeger for the Berthold Type Foundry in 1982. The company also includes various modifications or humorous features, such as cartoon modifications of their logo for use on holidays, birthdays of famous people, and major events, such as the Olympics.These special logos, some designed by Dennis Hwang, have become known as Google Doodles.
In 1998, Sergey Brin created a computerized version of the Google letters using the free graphics program GIMP. The typeface was changed and an exclamation mark was added, mimicking the Yahoo! logo. "There were a lot of different color iterations", says Ruth Kedar, the graphic designer who developed the now-famous logo. "We ended up with the primary colors, but instead of having the pattern go in order, we put a secondary color on the L, which brought back the idea that Google doesn't follow the rules."
In 2010, the Google logo received its first major and permanent overhaul since May 31, 1999. The new logo was first previewed on November 8, 2009, and was officially launched on May 6, 2010. It utilises an identical typeface to the previous logo, but the "o" is distinctly more orange-colored in place of the previously more yellowish "o", as well as a much more subtle shadow rendered in a different shading style. On September 19, 2013, Google introduced a new "flat" (two-dimensional) logo with a slightly altered color palette. On May 24, 2014 the Google logo was updated, the second 'g' has moved right one pixel and the 'l' has moved down and right one pixel. The old 2010 Google logo is still used on some pages, such as the Google Doodles page.
The first Google Doodle was in honor of the Burning Man Festival of 1998.  The doodle was designed by Larry Page and Sergey Brin to notify users of their absence in case the servers crashed. Subsequent Google Doodles were designed by an outside contractor, until Larry and Sergey asked then-intern Dennis Hwang to design a logo for Bastille Day in 2000. Hwang has been designing the Google Doodles ever since.
From time to time, Google shows a special colorless logo on a local homepage in recognition of a major tragedy, often for several days. The design was apparently first used on the Google Poland homepage following the air disaster that killed, among others, Polish President Lech Kaczyński in April 2010. A few days later, the logo was used in China and Hong Kong to pay respects to the victims of the Qinghai earthquake.
On September 8, 2010, the doodle once again changed to a greyed-out Google logo that lit up with the standard Google colors as the first 6 letters of a search query were entered. It goes by the name of the Keystroke Logo.
Google's favicon from May 1999-May 29, 2008, was a blue, uppercase "G" on white background. It was accompanied by a border with a red, blue and a green side. On May 30, 2008, a new favicon was launched. It showed the lowercase "g" from Google's 1999 logo, colored in white and originally was intended to be a part of a larger set of icons developed for better scalability on mobile devices. A new favicon was launched on January 9, 2009. It included background areas colored in red, green, blue and yellow. It was based on a design by André Resende, a computer science undergraduate student at the University of Campinas in Brazil. He submitted it for a contest launched by Google in June 2008 to receive favicon submissions. The official Google blog stated: "His placement of a white 'g' on a color-blocked background was highly recognizable and attractive, while seeming to capture the essence of Google". This is still being used on some portals. On February 1, 2012, a new favicon was being previewed. The lowercase "g" still retained its position but was shifted slightly up. The current favicon, launched on August 13, 2012, shows the small letter "g", but has a simple, light blue background color. It resembles the 2008 favicon.
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