It is a marriage of two of the world's biggest brands: Google has announced that the name of the latest version of its Android mobile operating system will be Android KitKat.

The internet giant has teamed up with Nestle, with the title following other sweet-themed names such as Android Cupcake and Android Jelly Bean.

There had been speculation that the latest version would be named Android Key Lime Pie.

Marc Vanlerberghe, director of Android marketing, said: "We couldn't imagine a better name for our Android K release than the tasty chocolate that's been a favourite among the team since the early days of Android."

Patrice Bula, Nestle's head of marketing, said: "We're excited to announce this partnership with Android, the world's most popular mobile platform, which will help us to enable even more KitKat fans to enjoy their break.

"KitKat is one of the world's top 10 fast-moving consumer goods brands in social media in terms of fan numbers and engagement.

"We continue to build on its strong digital presence with interactive, creative branding campaigns."

The release of Android KitKat will be marked with a competition to win prizes including 1,000 Google Nexus 7 tablets through more than 50 million specially-branded KitKat bars.

Consumers can take part by buying special packs of KitKat four-finger and KitKat Chunky multipacks available in Sainsbury's, Morrisons, Asda and Tesco.

The link-up comes as Google celebrates its 15th birthday today.

The firm has come a long way since September 4 1998, when it was incorporated by founders Larry Page and Sergey Brin, who had met at university three years previously.

It was originally called BackRub, but they eventually settled on the name for the website that has become synonymous with internet searching today - so much so that it is used as a verb in its own right.

Google was initially based in a garage, but now has more than 70 offices in more than 40 global locations, including London, with its headquarters - known as the Googleplex - in Mountain View, California.

Its size and reputation grew rapidly in the first few years, with three billion web documents on Google's index by December 2001.

Innovations subsequently launched by Google that have become part of everyday life include Google Maps, Google Streetview and Google Earth, each showing the breadth of the company's span across the globe.

Looking to the future, Google Glass is one of the internet giant's latest products, aiming to offer voice-activated hands-free connectivity through a wearable device.

Industry experts have praised Google for its success - but questioned how long it can stay at the top.

Joseph Lampel, professor of strategy at Cass Business School, City University London, said Google had to continue to innovate to make sure it stayed ahead of the curve to survive the next 15 years.

Professor Lampel said: "I am not surprised they have survived this far but if you're asking if they will survive until they are 25 or 30, that's another question."

He said there was increasing competition from search engines from emerging markets, especially those in Asia, and added: "Google might not be able to maintain their level of dominance, if the industry opens up to competitors.

"The question also arises of the very function of Google. The search engine business will shift in the next decade into new technology and new devices."

Prof Lampel attributed Google's success to its speed in adding services to their search engine and their push into hardware with products like Google Glass.

"All in all, they have done very well, and they have had an enormous influence, without question," he said.

Colin Cieszynski, senior market analyst at CMC Markets, said: "It's really incredible when you think about what Google has done over this period of time.

"They've taken a lead in the second wave of success of the internet, becoming the premier company. It's like there was a shake-up, and they're the ones who ended up on top. Yahoo has struggled along, but lots of others have fallen by the wayside.

"They have continued to innovate. The question is, how long do you manage to stay on top of everyone else?

"But this anniversary is incredible for them - they're still on top. To dominate for so long is amazing."

Despite the milestone date being reached, Google may not be marking the event until later in the month - having put out last year's Google Doodle to celebrate their 14th anniversary on September 27.

A Google spokeswoman would not be drawn on whether users could expect any birthday surprises during September.

Last year, a Google Doodle showed a birthday cake with 14 candles, which had slices removed until the name of the search engine emerged.