What is the button below the volume button and what is the function of this button?

It is a service that users can easily use applications, services and devices by reducing the execution steps through Voice (command) and Camera (Image recognition). It also recommends the personalized features based on the analysis of user's lifestyle at defined T/P/O. We named this service as "Bixby“. S8/S8+ has dedicated hardware key for Bixby home and Bixby (under volume key) to offer easy access to its interfaces.
 
Intelligence Service mainly consists of below different services.
- Bixby (Voice): Fast execution of app features and reminder through voice & chat
- Bixby Vision: Search the items and places through images in the gallery or camera app
- Reminder: Save the to-do-lists and content you want to watch again and show it later at defined T/P/O
- Bixby home (Automated Personalization): Personalized Apps and Services based on usage pattern.
 

Available features and content providers for Bixby may vary by country. Available launching schedule and language for Bixby Voice may vary by country the screenshot are subject to change.