Google Assistant[1] now lives on the iPhone. Its purpose lies in its name: to help you with your day-to-day life, be it set reminders, play music, fire off emails, give you directions, and tell you random facts, among other things. If you're thinking that's what Siri[2] is for, you're right. Except Google's offering can actually hold a conversation.
Ask Siri and the Assistant the capital of Uruguay, and they'll both give you the same response. (It's Montevideo, if you were curious.) But when you ask a follow-up question, say "What's the weather like?", Siri gives you the weather at your current location. It has already forgotten the query that came before. Google Assistant, on the other hand, can handle context, which allows it to give you the weather for Montevideo, and not where you are. You can then move the conversation forward, querying the best time to visit, or the places you should see.
That's one of the things that makes the Assistant slightly unique. The other is the way you communicate; you can chat with Google's digital assistant by either talking or typing, the latter of which Siri doesn't do. It's probably worth a mention that you could do the same inside Google's chat app, Allo[3], earlier but Assistant now available without that convolution, as a standalone app. The ability to type and interact means you can use the Assistant on the train, or in a meeting, without feeling like a dork.
At launch, the Assistant is capable of a lot. Apart from the functionality listed above, it can initiate calls, provide answers or translations, play games, fetch sports scores, set timers, look up stock prices, places nearby, or the definition of any word;...