Apple has billed the iPad as a new type of device; a combination of a smartphone and a laptop designed for multimedia consumption. It is capable of supporting games, videos, electronic books and magazines, as well as regular internet browsing.
The basic model of the device costs $499, with the top-spec version priced at more than $800.
Cath Turner, Al Jazeera's correspondent reporting from Apple's flagship store in New York, said: "This is a global event, I've spoken to people in line who have come from Greece and from Monaco just for the launch because this product won't be available to them for at least another few months."
Staff at the New York Apple store greeted customers with cheers after counting down the seconds to the iPad's 9am launch.
Adi Thomas, 38, had flown in from Australia to buy one. "It's slim, beautiful. I really want to get it home and play with it," she said.
Run on the same operating system as the iPhone, the iPad will support all the 150,000 applications currently available. In addition, developers are launching new applications for the device, and Apple is rolling out a new digital bookstore to provide content.
Since the California-based company unveiled the device in January, it has generated much excitement amongst technology enthusiasts, but some have pointed out that it is missing key features.
It lacks a camera, cannot run more than one application at a time, and does not support the Adobe's Flash format upon which many video websites are based. Reviewers say it is better for content consumption than content creation.
The iPad is only available in the US at present, although it is expected to launch in nine other countries later this month, when a high-spec version of the device will also be rolled out.
Apple's major competitors appear resigned to the iPad's success. Amazon.com, which offer the popular Kindle e-book reader, have released an application that allows people to read digitial books purchased from the Kindle store to work on the iPad.
Meanwhile Google, which analysts say is a potential competitor to Apple as the search engine giant moves into new sectors, has launched a version of its Gmail web mail application for the iPad.