In Short

During Google I/O 2016, Google Assistant was announced. While Google has been using voice search for years, Assistant builds upon a familiar platform in a whole new way, helping to better assist users in getting things done every day. Google Assistant is an ongoing two-way conversation that provides you with answers and information to whatever you may ask of it.

For example, you can ask "Who is the coach of the Boston Celtics?" and then followup with "How old is he?", and Assistant will know the context of the conversation, without you having to specify who "he" is.

Google Assistant will not just be on phones, but also tablets, wearables, cars and Google's new offering, Google Home. Also announced during I/O was Allo, a smart messaging app that will feature Google Assistant.