Apple has unveiled a top-of-the-range tablet called the iPad Air that is 20% thinner than the previous version.
The 9.7in (24.6cm) computer is 7.5mm (0.3in) thick and weighs 1lb (469g), which the firm claims is the lightest full-sized tablet on the market.
It is powered by the same A7 chip found in the company's iPhone 5S.
The launch comes at a time when some analysts have suggested that Google's Android is about to overtake Apple's iOS as the bestselling tablet platform.
Apple also announced a new version of its iPad Mini.
Its 7.9in (20cm) screen has been upgraded to feature 2048 by 1536 pixels - the same as the larger model. It is being branded as "retina" to highlight the increased resolution.
Amazon and Google have already announced small tablets - the Kindle Fire HDX and Nexus 7 - with similar high definition displays.
"We've got the retina（视网膜） upgrade to the smaller iPad that many thought should have been there in the first place," Tony Cripps, principal analyst at tech consultants Ovum, reflected after the announcement in San Francisco.
"Market share slip is inevitable because so many rival devices are coming out, which is not necessarily a bad thing as the overall sector is growing.
"Apple does now have a cheaper model thanks to it offering the original iPad Mini at a lower price - but the firm doesn't really want to go to the low-end because that's not where the greatest profit is extracted."
Apple also announced that the latest version of its Mac operating system, Mavericks, would be offered at no cost to owners of computers already running any version of OS X released since 2009. It is the first time the company has not charged for a major Mac OS upgrade.
By contrast the full version of Windows 8.1 is sold for about £100, although it is free to existing Windows 8 users.
Linux-based Ubuntu has always been offered without charge. Chromebook computers also get free upgrades for Google's PC operating system.
New laptops, productivity and leisure apps were also unveiled. However, Apple did not show off a new TV set-top box as some had speculated.