By now, some of you may already be familiar with Google Now, a predictive personal assistant for our mobile devices. Whether you have or haven't, though, do you really know what it is and how it works?

The premise behind Google Now was as cool back when it launched as it was creepy: Let Google track everything you do on the web and in return your phone will be graced with a voice-activated assistant and a steady stream of “cards” full of personalized, pertinent information.

When the service launched it was only available to Android smartphone users. Today, Google Now is available on iOS as well as desktop implementations of Google’s Chrome browser.

Related: Wearable Wars: 3 Reasons Why 'Android Wear' Will Rule the Wrist

Leveraging Now’s full strengths requires using Gmail, using Google Chrome as your primary browser on as many devices as possible, and allowing Google to track your web activity. In exchange, the system learns where you live, work, and frequently travel, what stocks and sports teams you track, what TV shows, movies and music you’re interested in, what packages you’ve sent and are expecting, and so on.

Sound a little creepy? We agree, but Now can provide timely updates on traffic and weather conditions, stock prices and sports scores, movie and TV listings, and package tracking info. It also suggests web content based on your recent search and browsing history and -- of course -- offers voice-activated web search and control over select smartphone functionality.

And that’s just for starters. Google Now is constantly being expanded to keep tabs on new types of information.

Related: Does Anybody Really Need a '2K' Smartphone?

For my money, Now really shines in its Android implementation. Now’s bite-size bits of information are custom tailored to the mobile OS’s widget system, and many recent Android phones offer easy access to the Google Now app itself via a swipe or gesture. Now’s user interface allows for easy dismissal of information you’re not interested in and tweaking of settings to sharpen the service’s utility. The app also integrates quite well with Google Maps for Android, offering turn-by-turn navigation with real-time traffic updates.

The next frontier for Google Now is your wrist. Google’s recently announced “Android Wear” software will power a new wave of smartwatches and other wearable computers set to debut later this year. The technology’s called Android Wear, but it’s clear to anyone who’s seen the demo video that this is essentially Google Now for your wrist. The personal assistant is about to get even more personal.

Related: How the HTC One M8 Smartphone Stacks Up to the Competition