The Mac OS X operating system has seen some impressive growth this year, according to Chitika Research (, a full-service on-line advertising network serving over 2 billion monthly impressions across more than 80,000 websites.

From January through March, Mac computers made up just over 7% of the market share, according to traffic numbers coming into the Chitika advertising network. In April, however, that number spiked to 10.25%. Perhaps thanks to the increased foot traffic at Apple stores across the U.S., the Mac managed to pick up 3% of the home computer impressions market over the course of a single month.

Apple’s main competitor in the operating system business, market leader Microsoft, bore the brunt of the shift — between March and April, 2010, the market share of Microsoft’s Windows operating system dropped from 89% to just over 85%, says Chitika. Linux, the open-source operating system favored by many tech professionals, has remained mostly steady in 2010, with just under 1% of the operating system market.

Market share numbers are based on a sample of 1,931,369,632 impressions across the Chitika advertising network between January and April, 2010.

“It’s hard to say what the cause of the OS X spike in impressions in April is,” says Chitika. “It’s hard to believe the iPad truly drove that many sales of Macs, and there are other possibilities — more existing Mac usage, a higher proportion of Macs being used for web-browsing, or other reasons — but the impression growth is impressive, and should bode very well for the future of Apple.”