MacBook Pro. Photo: Apple

Apple's (NASDAQ:AAPL) Macs are not as popular as Windows-powered PCs. Apple's share of the traditional PC market has risen in recent years, but by most metrics it continues to hover in the single digits. Apple sold 5.7 million Macs in the third quarter, while Microsoft's (NASDAQ:MSFT) hardware partners shipped more than 60 million traditional PCs, according to research firm Gartner.

But Apple's Phil Schiller has a different take on the Mac. In a recent interview with Mashable, the Apple marketing chief argued that Apple's share of the traditional PC market may be quite a bit higher.

Approaching 25%
Here's Schiller speaking to Mashable's Lance Ulanoff:

"There are endless numbers of stats out there, you can quote any of them to tell any story, but the number that closet reflects what we all experience and see as we travel around is actually a U.S. market share approaching 25%...That closer reflects what we see when we go to the airport, when we go to the coffee shop, when we go to schools. You increasingly are seeing more Macs than PCs."

Schiller qualifies his market share claim with two important distinctions: first, he's only taking about U.S. market share, and second, he's only speaking about the sort of PCs one is likely to encounter among consumers -- not the many machines sitting in the cubicles of Fortune 500 workers.

Apple's Macs are certainly more popular in the U.S. than in other markets. According to research firm IDC, Apple's share of the global PC market was 7.8% in the second quarter, but its U.S. market share was higher -- 13.5%. In total, Americans purchased about half the Macs Apple sold in the second quarter. IDC doesn't draw a distinction between consumers and business users, but NPD confirmed to Mashable that, among consumers, the Mac's U.S. market share is near 25%.

The importance of the Mac business
Apple derives around two-thirds of its revenue from the iPhone, but the Mac is its second-largest business. Last quarter, the Mac generated about 13% of Apple's revenue -- $6.9 billion.

The Mac also serves an increasingly important strategic role in Apple's broader ecosystem. Last year, Apple introduced Handoff, a new feature included in OS X Yosemite. Apple's Macs function well as stand-alone devices, but serve their owners better when paired with Apple's smartphone. iPhone owners can answer calls through their Mac, and in certain apps -- including Safari and Mail -- pick up where they left off. This appears to be a long-term strategic aim for the company, as Apple's latest OS X update, El Capitan, pushed the concept further. "The best thing about El Capitan is that it makes iOS better," declared The Next Web's Nate Swanner.

Microsoft targets the Mac
Schiller's comments come on the heels of unprecedented aggression from Microsoft. Early in October, Microsoft unveiled the Surface Book, the first laptop from the Windows-maker. Microsoft has marketed the Surface Book as a MacBook Pro killer, explicitly encouraging Mac owners to ditch their machines for its new PC. The Surface Book remains fundamentally a Windows computer, with all the issues and complications that entails, but it sports top-notch hardware and has received strong reviews.

Microsoft's hardware partners have long offered a wide variety of machines, but haven't been able to stop the Mac's steady march. Free of the bloatware that often plagues Windows PCs, and sporting a unique design, the Surface Book may be the first computer that poses a risk. 

But for the time being, Apple's Mac business is in great shape. Mac unit sales rose 3% on an annual basis last quarter, while the broader PC market fell almost 11%.