"Within two weeks after releasing, our app has achieved more than half a million downloads, which is a lovely surprise for our team," said Peggy Dai, a Microsoft programme manager.

"Together with the research team we will introduce more innovative features to the app, and expand availability on more platforms," she continued.

Microsoft has released a series of apps recently, including an Android-only alarm clock that requires the user to perform tasks — such as smiling or finding an object — to switch it off.

The backbone of these projects is artificial intelligence and machine learning, which is an important goal for the company. Microsoft's Garage team, a small group of engineers and developers who make one-off fun apps, has produced multiple apps that seem silly but actually showcase AI.

The success of the apps is, in many ways, not as important as the development of them. The fact that the Selfie app is successful is a "surprise" to the team shows this.