Remember when market research firms were predicting the impact of tablets? Some were skeptical, considering the boom and relative bust of netbooks. But tablets are officially mainstream and seemingly have staying power.

According to market research firm Gartner Inc., worldwide tablet sales to end users reached 195.4 million units in 2013. That’s a 68 percent increase over 2012. Drilling down into operating systems, iOS tablets grew in the fourth quarter of 2013 but iOS' market share declined to 36 percent in 2013.

Gartner reports the tablet growth in 2013 was fueled by the low-end, smaller screen tablet market, and first-time buyers. This led Android to become the number one tablet operating system, with 62 percent of the market.

Android vs. Apple

"In 2013, tablets became a mainstream phenomenon, with a vast choice of Android-based tablets being within the budget of mainstream consumers while still offering adequate specifications," said Roberta Cozza, research director at Gartner. "As the Android tablet market becomes highly commoditized, in 2014, it will be critical for vendors to focus on device experience and meaningful technology and ecosystem value -- beyond just hardware and cost -- to ensure brand loyalty and improved margins."

In 2013, the share of Apple's iOS dropped 16.8 percentage points as the market demand was driven by the improved quality of smaller, low-cost tablets from branded vendors, and low-end, low-cost products continued to grow in emerging markets. Gartner analysts said emerging markets recorded 145 percent growth in 2013, while mature markets grew 31 percent.

We turned to Michael Disabato, managing vice president of network and telecom at Gartner, to get his take on the Apple versus Android tablet battle. He told us if there was more than one iOS vendor, iOS would be on top of the market -- and if Apple cared about being the market leader, the company would drop its prices.

“Android licenses are inexpensive compared to the iPad. A lot of people are looking at tablets as a potential computer replacement. If you can get everything or almost everything you want on a tablet, why would you want a PC? And if you don’t want to pay what Apple is charging, then you are going to get an Android tablet,” Disabato said. “So tablets are accelerating -- and because Android is cheaper, Android tablets are accelerating.”

Lenovo Rising

Moving on to Microsoft, the software giant’s tablet volumes improved in 2013 but share remained small, according to Gartner. Cozza said in order to compete, Microsoft needs to “create [a] compelling ecosystem proposition for consumers and developers across all mobile devices, as tablets and smartphones become key devices for delivering applications and services to users beyond the PC."

What about all the rest? Among vendors that have less than 6 percent shares of the worldwide tablet market, Gartner reported that Lenovo did particularly well in 2013, with tablet sales growing 198 percent.

"Lenovo‘s success is a combination of launching innovative new tablet models during the second half of 2013 and the sales of its Yoga model and Windows tablets doing particularly well," said Isabelle Durand, principal research analyst at Gartner.

Durand said that Lenovo has been able to introduce innovative and a range of attractive products to the market because of its strong R&D capabilities as well as its ability to react quickly to tablet market dynamics. However, she added that the company still faces challenges establishing a strong brand with consumers outside China, which is particularly important in the tablet market.