PC shipments and sales are declining. It’s an undeniable fact. What people can’t seem to agree on is the cause. Some say the rise of tablets and smartphones are to blame, while others think it’s just a longer than usual …

The PC industry will see its sharpest unit decline in history, with shipments totaling 257 million units in 2009, an 11.9 percent decrease from 2008, according to Gartner.

Previously, PC units had their worst decline in 2001 when unit shipments shrank 3.2 percent.

"The PC industry is facing extraordinary conditions as the global economy continues to weaken, users stretch PC lifetimes and PC suppliers grow increasingly cautious," said George Shiffler, research director at Gartner.

Global PC shipments grew by 14.6 percent to 69.5 million units in the first quarter of 2008, which beat previous estimates of 13.2 percent according to IDC’s Worldwide Quarterly PC Tracker.

The U.S. market showed signs of the economic slowdown, but growth remained positive at 3.5 percent for the quarter. The other international markets compensated for the U.S. coming in more than 2 points above estimates due to continued strength in developing countries.

PC shipments worldwide reached 61.1 million units in the second quarter of 2007. There was an 11.7 percent increase from the same period last year according to Gartner.