According to IDC’s latest numbers, in the third quarter, overall wearable device shipments were as high as 21 million units worldwide—a growth of 197.6% year-over-year. And this year’s launch of the Apple Watch has contributed to the increase, with IDC reporting 3.9 million units of the iPhone-connected device shipping in the third quarter. But even though Apple (“AAPL”) has had significantly more success with its smartwatch than brands like Motorola and Samsung, the company is still taking a back seat to Fibit (“FIT”), which is known for its lineup of activity-tracking gadgets from the $60 Zip to the $250 Surge. Fitbit commanded 22.2% of the wearable market share in the third quarter, continuing its dominance as the segment’s number one vendor.

To see why Fitbit and Apple are ahead of the pack in this still-young market, you need only look at their closest competition. Following Fitbit and Apple are Xiaomi, a Chinese manufacturer with an inexpensive activity tracker called the Mi Band; Garmin, known for its GPS fitness watches; and BBK, a Chinese electronics brand that sells a smartwatch for kids. Even though it sells fitness bands such as the Vivosmart, Garmin is best known for its GPS-equipped running watches and wearables that cater to more professional athletes across a number of sports. As for the other two brands, neither has yet to make a splash with worldwide wearables sales, though Xiaomi’s numbers in particular (3.7 million units shipped in the most recent quarter) are nothing to sneeze at.

As to why Fitbit is the most successful vendor when it comes to fitness band sales, IDC research analyst Jitesh Ubrani sees several factors working in the brand’s favor. “They’ve done a great job at spreading awareness and targeting the growing segment of fitness trackers,” he says. “Apart from great devices, Fitbit’s partnerships with fitness- and health-focused companies [like MyFitnessPal and Runkeeper] and their growing distribution network have been key in maintaining their lead.” Ubrani also points to the company’s efforts in the enterprise sector, through corporate wellness programs, as increasing brand awareness for the company.

Since it is still early days for smartwatches, which are still negotiating the delicate balance between form and function, wearable shipment data could paint a very different picture a few years down the line. For instance, activity trackers are relatively well established today, but the wider adoption of smartwatches such as the $349-and-up Apple Watch and Android Wear devices may be a longer-term trend. However, with Xiaomi and its sub-$20 Mi Band taking third place according to IDC, it’s fair to wonder whether this Chinese brand, not to mention other manufacturers such as Jawbone, could overtake the reigning champion.

“It’s going to take more than just price to be a leader in the market,” says Ubrani, who says that while the Mi Band is already available in the U.S., Xiaomi’s sales volume in the states has been low. “In order for this to change, they have to exponentially increase marketing and distribution.”

Fitbit, however, has managed to dominate the wearable market through a combination of marketing savvy and compelling software. Its apps and desktop dashboard provide a comprehensive look at fitness information, along with the option to connect and compete with friends. Incidentally, it is similar features on the Apple Watch—such as its ability to log basic fitness metrics and to communicate with fellow iOS users through the touchscreen—that have also made Apple’s smartwatch such a standout device.

Jibrani sums it up thusly: “Fitbit does well because it’s built a community and helped make fitness a more social experience—they’ve created staying power.” But with other wearables continuing to evolve and add new features, there’s no saying that Fitbit—let alone any other fitness band maker—will hold the number-one spot in years to come.

For more details on Fitbit, watch this Fortune video: