At the opening Google I/O Keynote, Google’s CEO Sundar Pichai announced Google Assistant. A virtual assistant that can converse with you and help you find the relevant information you need.
Building on Google Now and the technology behind it, Google Assistant is able to hold more better conversations with you that will allow it to show better contextual results and do things for you.
The assistant is also able to answer follow up questions in reference to your original questions. So, you can, for example, ask when the Eiffel tower was built and then proceed to ask Google who built it, without the need for mentioning Eiffel tower again.
In the demos that Google showed for Google Assistant at the opening keynote, the assistant was able to provide you with movies playing in nearby movie halls, pull up their reviews, and even book tickets for it. In another demo video, Google showed the Assistant being used in an Android Auto-compatible infotainment system inside a car to order curry.
From what it looks like, Google Assistant is the successor of Google Now and Voice Actions and will be available across all Android devices, including smartphones, Android Auto, and Android Wear.