Bixby is the Samsung assistant
Bixby is a virtual assistant designed by Samsung that is present on the Galaxy S8, in the future the assistant may also be available on other Samsung devices. The idea behind Bixby is that it will help you with the tasks you want to carry out with your phone, which makes it a bit different from other assistants like Google Assistant, Microsoft Cortana, Apple Siri or Amazon Alexa. With Bixby you can operate the phone more with a single voice (and therefore less focused on facts or searches).