Apple's iPad further dominates with 68% share of tablets shipped

Apple's strong performance handily beat the second-place tablet maker, Samsung, which took 9.6 percent of the market with 2.4 million units shipped, according to IDC. Apple actually improved its market share from the second quarter of 2011, when it accounted for 61.5 percent of tablets shipped.

Coming in third in the second quarter of 2012 was Amazon, as the company was estimated to have shipped 1.3 million Kindle Fires, giving it 5 percent of the market. Asus came in fourth with 855,000 units shipped and 3.4 percent, while Acer took fifth with 385,000 units and 1.5 percent.

In all, IDC estimates that 25 million tablets were shipped in the second quarter of 2012, of which Apple accounted for just over 17 million. The overall tablet market grew 66.2 percent year over year, behind Apple's 84.3 percent growth from the same span in 2011.

"Apple built upon its strong March iPad launch and ended the quarter with its best-ever shipment total for the iPad, outrunning even the impressive shipment record it set in the fourth quarter of last year," said Tom Mainelli, research director, Mobile Connected Devices. "The vast majority of consumers continue to favor the iPad over competitors, and Apple is seeing increasingly strong interest in the device from vertical markets— especially education.

"While iPad shipment totals are beginning to slow a bit in mature markets where the device saw early traction, growth in other regions is clearly more than making up the difference."

IDC has predicted that the tablet market will become more competitive in the second half of 2012, with the recent launch of Google's Nexus 7 and Microsoft's forthcoming Surface tablets. However, the research firm said users may also be simply overwhelmed and confused by the number of devices available on the market.

"If anything, there's a real risk that people will have too many options from which to choose this holiday season," said Bob O'Donnell, IDC program vice president for Clients and Displays. "Consumers baffled by the differences between Amazon and Google versions of Android, or Windows 8 and Windows RT, may well default to market leader Apple. Or they may choose to remain on the sideline for another cycle.