In 2012 and 2013 there were claims the tablet industry would stomp out the personal computer business, ending the once great PC for a smaller and more mobile device.

However, it looks like tablet sales have peaked in 2014, at least for the iPad. Reports show four straight quarters of decline for the most popular tablet worldwide, despite still holding more than 60 percent of the tablet market.

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Worldwide shipments for tablets are slowing down. Research group IDC claims year-on-year growth will continue to fall. Some analysts believe the tablet market will shrink by 2018, with the adoption of phablets in Asian countries outpacing tablet sales.

Tablets are devices ranging from 7 to 12-inches. There is some misinterpretation on what is a tablet and what is a laptop, mostly due to the convertibles brought in by the launch of Windows 8. Anything running Windows 8 is still considered a computer, regardless of size.

Other than increasing growth in the phablet market, tablets owners seem to be holding on to their devices for much longer than expected. The iPad 2 is still the most popular iPad ever - this may be due to Apple failing to deliver on the iPad 3 and iPad 4.

Android tablets do not appear to be closing the gap either, despite new tablets like the HTC Nexus 9 and Samsung Galaxy Note 10.1 showing potential against the iPad.

Phablets range in size from 5.5-inch to 6.5-inch devices. What used to be considered folly is now customary for many smartphones, like the iPhone 6 Plus, Galaxy Note 4, Huawei Ascend Mate and other phablet devices.

These phablet devices are extremely popular in Asia, where the iPhone 6 Plus and Galaxy Note 4 are seeing the most success. The popularity has spurred regular smartphone makers to increase the display size above 5-inches, to attract more buyers.

The new iPad Air 2 and iPad Mini 3 might be other factors that play into Apple's decline in Q3 and Q4 sales. The company has added minimal upgrades to both tablets, clearly stuck when it comes to innovative features for tablets.

Apple has not responded to comments on the decline of iPad sales. CEO Tim Cook recently said the iPad is still a core product in the lineup, but Mac surpassed it in sales last quarter, showing a resurgence in PC and Mac sales.

TagsIpad, Tablet, iPad Air 2, iPad Mini 3, phablet, PC