Google Now has long helped Android users get timely information about local traffic, movies that are playing locally and other information based on their commutes, browsing history and other data. With Android M, which Google announced today, the Now service is getting even smarter and more contextual. When you tap and hold the home button in Android M, Google will grab the information from the application you are using at that moment and Now will try to give you the right contextual information about what you are looking at in that app. Google Calls This ‘Google Now on Tap.’

As Google’s VP of Products Sundar Pichai noted in today’s keynote, this is really an extension of Google’s overall search strategy and the result of its efforts around machine learning and deep neural networks to help computers understand more about the world around them.

You can also invoke this feature by saying “Ok Google” at any time and then ask a question related to the app you are looking at, or by tapping on a word in an article you are reading, too.

Here is how this works in practice. Say you are playing a song in Spotify. Tapping and holding the home button will bring up more info about the song you are looking at. But you can also do a voice query and ask: “Who is the lead singer?” Google Now already knows what song is playing and using data from the Knowledge Graph project — it can (hopefully) answer your questions.

Similarly, this service can work its magic from Hangouts, for example. Say you are discussing “the new George Clooney movie” with a friend. Bringing up Now On Tap will give you more information about Tomorrowland, because Google knows that’s what you are talking about. Some of the information you can expect to see are movie times, reviews and maybe more information about the actors in the film. Because of Google’s App Indexing project, it can also recommend related applications (maybe IMDB or Flixster) and deep links into them (if you have them installed). If your friend had asked you to remember to buy tickets for the movie, Google Now would also have popped up a box to set a reminder for you.

Google Now on Tap uses a couple of built-in operating system-level features from Android M, so this service won’t come to older Android versions. The reason for this, Google Director of Product Management Aparna Chennapragada tells me, is that this is the only way to make sure that this service works with any application.

Developers won’t have to do anything to enable this feature in their apps. The platform API will simply handle all of this for them. If they want to, though, they can add some specific metadata to their apps to help Google figure out what exactly is happening in the app. This means a game developer could add information about what level you are on, for example, and Now on tap can then pop up relevant info about that level. Without the metadata, Google wouldn’t be able to easily get this information from the game, after all.

Chennapragada tells me that all of this happens on an opt-in basis. You have to enable this feature in Google Now and then the only time you exchange information with Google is when you actually do the ‘tab and hold’ gesture. No data is copied between your app and Google until you ask it to do so.