The sun beats down on a vast green canvas. The squawk of a robin echoes through the trees. As the breeze picks up, the rustle of leaves offers the soundtrack for a restful afternoon on the links. The only tools needed are a ball, a tee and some clubs.

Oh, and your cell phone.

Once considered an affront to the peaceful serenity of golf, mobile phones are quickly becoming tools for slicing handicaps and lowering scores.

Thanks to new apps that rely on GPS technology, the days of wandering around a fairway searching for a yardage marker are over. The everyday duffer now has advice in the palm of his hand that, until a few years ago, you could only get from pricey standalone units or personal caddies.

Want to know exactly how far it is from the tee to the front of that fairway bunker? Is it really only 125 yards to the green from here? A few taps on your phone and you know.

Applications like Viewti Golf 2010 ($29.99 iPhone), GolfLink Game Tracker ($14.99 iPhone), Golfshot ($14.99 iPhone) and GolfLogix ($39.95, multiple devices) offer feature-packed tools designed to help you keep score, find distances and review your game over a beverage at the 19th hole.

The feature sets and prices vary (Viewti, for instance, offers video swing analysis), and most offer a free version with a limited feature set, but here are the basics you’ll find in most apps.

• Access to thousands of courses. • The ability to keep score for an entire foursome. • Tracking for number of putts, greens in regulation and fairway drives. • GPS rangefinder to measure distances to hazards and greens and the length of your most recent shot. • The option to publish your score online. • Cumulative stats for all of your rounds.

So how do these touch-screen caddies work? Pretty simply, actually. I’ve only used the GolfLogix app, but all work off the same basic foundation. Choose a course and options for that round, start your session, and from there it mostly moves by itself. After you hit your first shot and arrive at where it landed, you’re told how far you hit that shot.

Then, using the touchscreen, you can tap a spot on a satellite view of the hole indicating where you want your second shot to land, for instance if you wanted to lay up to a water hazard. It will then tell you how far it is to that spot. If you’re close to the green or on a par 3, you’ll see the distance to the front, middle and back of the green. Once you finish the hole and advance to the next tee, the GPS recognizes you’ve moved on and asks for your score. That’s it.

Newer apps and updates to current ones are adding social integration as well. And it’s not just for iPhones. Some apps are available on multiple mobile platforms including Android, Blackberry and Palm. Microsoft’s Windows Phone 7 hasn’t been released but there’s already a demo of a potential golf app.

“I think they’re great,” PGA Professional Doug White of Barton Hills said. White hasn’t personally used the phone-based apps but has played with similar GPS devices and has seen many at Barton Hills using the new technology. “Anything that helps a player find their yardage and play their shot is a good thing. It could be very beneficial to the pace of play. Now they need to make one that helps you find your ball, too.”

There are some drawbacks, however. First, if your phone isn’t fully charged before a round you’ll have a hard time finishing before it drains. Lowering the screen brightness of your phone to at least 50% will help on batter life. Second, when playing in inclement weather you’ll have to decide if your phone can stand some rain. White also mentioned that while GPS devices are legal at tournaments pending local rules for each course, the iPhone versions may offer more than just distance information and therefore be outlawed in tournament play.

There’s also no guarantee that technology will help you play faster. In fact, it could be the opposite. If you’re the only person in your group with the app, you’ll quickly find yourself doling out yardage info to your playing partners instead of preparing for your next shot. And you could quickly find yourself the scourge of the links if you forget to put your phone on silent mode.

Despite any potential issues, there’s little doubt these apps can help polish your game. Club selection is a struggle for even the lowest handicap players. Knowing not only the exact distance to the hole but also seeing on the screen how far you hit every club in your bag might not put you on the PGA Tour, but if it shaves a couple strokes off the score, that might be enough.