The tablet computer market is heating up with new entrants all the time, but Apple's iPad will remain the top device over the next few years, according to technology research company Gartner.
Gartner, in a forecast released Monday, said mounting competition will see Apple's share of the touchscreen tablet market decline but the iPad will still make up nearly half of all tablets sold in 2015.
Gartner said the iPad will account for 47 percent of worldwide sales of 294.3 million tablets in 2015, down from 63.5 percent of 108.2 million units to be sold in 2012 and 68.7 percent of 69.7 million tablets to be sold this year.
The iPad, which was released in April of last year, accounted for 83.9 percent of the total 17.6 million tablets sold in 2010, according to Gartner.
Gartner said tablets running Google's Android operating system will see their market share rise steadily -- from 14.2 percent last year, to 19.9 percent this year, to 24.4 percent in 2012 and 38.6 percent in 2015.
Tablets running Blackberry maker Research In Motion's QNX software will claim 5.6 percent of the tablet market this year, 6.6 percent in 2012 and 10.0 percent in 2015, Gartner said.
The only other significant player in Gartner's forecast was Hewlett-Packard with tablets running the WebOS operating system acquired from Palm.
WebOS tablets were forecast to have 4.0 percent of the market by the end of 2011, 3.9 percent by 2012 and 3.0 percent by 2015.
Microsoft, which has been marketing its Windows operating system to tablet makers around the world, was notably absent from the Gartner forecast.
Blackberry's first tablet, the PlayBook, goes on sale on April 19.
Gartner research vice president Carolina Milanesi said "it will take time and significant effort for RIM to attract developers and deliver a compelling ecosystem of applications and services around QNX to position it as a viable alternative to Apple or Android.
"This will limit RIM's market share growth over the forecast period," Milanesi said.
"It will be mainly organizations that will be interested in RIM's tablets because they either already have RIM's infrastructure deployed or have stringent security requirements," she said.
Milanesi said that in general, "smartphone users will want to buy a tablet that runs the same operating system as their smartphone.
"This is so that they can share applications across devices as well as for the sense of familiarity the user interfaces will bring," she said.
Explore further: Microsoft unveils Xbox in China as it faces probe