Market research firm ,Canalys found that due to strong sales of lucrative iPad, Apple shipments are beyond the traditional PC plant.In the fourth quarter,Apple became the world's leading client PC factory, shipped more than 15 million iPad and 500 million units Mac, accounting for 17% of total client PC shipments in the fourth quarter, HP's market share was approximately 12.7% which was far behind, ranking second in the world.The CEO of Canalys ,Steve Brazier said: "We are about to experience the biggest transition period since 20 years in the PC industry." For example, the notebook which was popular a few years ago has now been exhausted the massacre by iPad, which is a big problem for Hewlett-Packard. The netbook means 10-inch the small computer equipped with Windows.According to Canalys, excluding Tablet PC, the client PC market fell 0.4%.Canalys said that in the other five major PC plants, only Lenovo's market share increased by 2 percentage, on the other hand Apple has the annual growth of 6 percent at the same quarter. Hewlett-Packard, Acer and Dell's market share declined over the same period. Currently, Amazon's shipments of flat-panel computer KindleFire,may be more than 500 million units at fourth quarter, if the sales of Fire and other Kindle devices are together, then the total sales volume will challenge top PC plant.