Google is hoping to build the world's largest digital filing cabinet in the latest attempt to deepen people's dependence on its services.

The internet search leader began its pursuit of the audacious goal yesterday with the much-anticipated debut of Google Drive, a product that stores personal documents, photos, videos and a wide range of other digital content on Google's computers.

By keeping files in huge data centres, users will be able to call up the information on their smartphones, tablet computers, laptops and just about any other internet-connected device. Content can also be more easily shared among friends, family and co-workers by sending links to the information instead of emailing large attachments.

Google Drive is offering the first five gigabytes of storage per account for free. Additional storage will be sold for prices starting at US$2.49 ($3.07) a month for 25 gigabytes, up to US$49.99 a month for one terabyte, equivalent to five laptops with 200-gigabyte drives.

The service is initially available for installation on Windows-based computers, Mac computers, laptops running on Google's Chrome operating system and smartphones powered by Google's Android software.

A version compatible with Apple's hot-selling iPhone and iPad is due in a few weeks.

It may be several weeks before Google Drive is available worldwide.

Offering online storage is part of a technological shift away from storing personal files on a single machine in a home or office to entrusting them to computing hubs accessible just about any time at any place with internet access. The concept has become popularly known as "cloud computing".

For all its technological know-how, Google is a late arrival in what is shaping into the internet's version of storage wars. Other combatants with a head start include two other technology heavyweights, Apple and Microsoft, and pioneering startups such as Dropbox and Box.

Google is hoping to further differentiate its storage service by equipping it with more convenient and powerful tools. Google Drive will draw upon the company's expertise in internet technology for text and images to make it easier to find data quickly. It also includes optical character recognition that can search for specific words in scanned newspapers or other sources.

Google is entering the fray five years after word first leaked out that the company was developing an online file storage service, then called Gdrive. It never came to fruition.

But Google still has plenty of time and, more importantly, plenty of firepower to topple the competition, says Gartner analyst Michael Gartenberg.

"This puts Google into the heart of the battle," he said. "We are entering this era where the personal cloud is going to be more important than the personal computer, so to remain relevant Google needed a service like this."

It marks Google's second foray into online storage. Following Apple's lead, Google last November opened a music store that included free storage for up to 20,000 songs per user.

Google Drive is starting out by undercutting the five-year-old Dropbox, which has emerged as an early leader in online storage by attracting more than 50 million users who collectively sync about 1 billion files every two days.

Dropbox offers only 2 gigabytes of free storage, less than half of Google Drive, and sells 100 gigabytes for US$20 a month or US$200 annually.

Google Drive will charge just US$5 per month, or US$60 annually, for 100 gigabytes of storage.

Apple's iCloud service, designed for owners of its mobile devices and computers, also offers 5 gigabytes of free storage and charges US$100 annually for 50 gigabytes of storage. Microsoft's SkyDrive offers 7 gigabytes to 25 gigabytes of free storage, depending on when the user signed up. In a move that may have been driven by Google Drive, Microsoft announced this week that SkyDrive would sell 100 gigabytes of storage for US$50 annually.

Dropbox indicated it is counting on its unwavering focus on online storage to fend off Google, which has diversified from internet search into email, photo sharing, social networking, online video and smartphones.

"Companies of all shapes and sizes have tossed in their hats over the years, but we've stayed ahead by building the best possible experience and making a product that millions of people love," Dropbox said.

Dropbox, started in 2007 by two graduates from the Massachusetts Institute of Technology, is backed by US$257 million in venture capital. Reports yesterday put Google's operating cash flow at US$15 billion.

But Google's deep pockets haven't always been enough for the company to overcome the early lead of smaller companies that carved out new niches on the internet.

It hasn't been able to build an online social network to surpass Facebook, despite years of trying.

But Google has the advantage of being able to dangle the storage service in front the more than a billion people who already use its internet search engine or other popular products that include Gmail, its YouTube video site, online software suite Google Docs, social networking service Google Plus and smartphones running on Android.

If Google Drive takes off, the company will become a bigger custodian of sensitive data. Privacy watchdogs fear Google already knows too much, but Gartenberg doubts those concerns will undermine Google Drive.

- AP