Before the Apple Watch, smartwatches were ugly, bulky monstrosities with no style and limited appeal. All that changed the moment Apple CEO Tim Cook announced that he had “one more thing” to show off during the September iPhone event in 2014. It was only a teaser, but it was the defining moment of the wearable category.

From that moment on, Samsung, Huawei, LG, and Motorola got serious about design. They invested in stylish smartwatches with a selection of bands and colors – just like the Apple Watch. Some, like Motorola and Huawei, even offered styles designed to appeal to women. Before the Apple Watch came in with its smaller 38mm casing, rose gold color option, and snazzy feminine watchbands; women didn’t even have the option of wearing a stylish smartwatch that would fit their wrists. Apple was the first to recognize the untapped potential of women as smartwatch buyers.

The Apple Watch is a true breakthrough product — It defined an entire category of devices and set the standard for every other smartwatch.

When it finally arrived in April 2015, the Apple Watch grabbed the world by the wrist. For the first time, I saw smartwatches in the wild on people who were not tech journalists or men, and every single one of them was an Apple Watch.

The Apple Watch brought style, choice, and awareness to the smartwatch market, but it also introduced a better interface and exposed some of the problems in Android Wear. Even at launch it offered a wealth of apps, and developers hustled to pile on more in the following weeks and months. Watch OS 2 brought native apps, which live on the watch instead of your phone and improve the overall experience. The ability to tap to pay with the Watch was another key first, and a feature that has yet to be added to Android Wear, though it will hit Samsung’s Gear S2 soon.

The Apple Watch is our top pick for the best mobile device of 2015 because it is a true breakthrough product that defined an entire category of devices and set the standard for every other smartwatch made over the course of the year.