A shutter release is a tool found in nearly all photographers' bags. The reason why this tool is so useful is that it allows a photographer to take a picture without touching the camera. A shutter release acts as a remote for your camera so you can take pictures a certain distance away from a camera.
The tool has often been used for still photography, removing any shake or vibration from a camera from the photographer's hand. It is also particularly useful for long exposure photography where the shutter needs to stay open for a long period of time.
There is now a new product that acts as a shutter release for smartphones. The one shown is called the HISY and it works for Apple products (HALO for Android products). The device connects to the phone via bluetooth. It can take photos or start and stop video. The device can work from about 90feet away.
As for practical use, the company really tries to sell this to people trying to take perfect selfies or group photos. However, it could be used in many different ways. The only thing limiting you is your creativity!