In the summer of 2009, Yelp quietly added a feature to its iPhone app that blurred the line between the real and the virtual. If you held your handset up and looked at the world through its screen, you’d see little floating tags containing the names, user ratings, and other details of businesses around you. 

The feature, called Monocle, was an experiment with augmented reality—one of many that appeared around this time, as companies tossed around various ways to mesh digital content with the real world, hoping to catch consumers’ eyes (see “TR10: Augmented Reality” and “New Reality”).

Several years later, augmented reality is still mostly used by early tech adopters, but it’s starting to graze the mainstream, helped by the massive popularity of smartphones and tablets, and their constantly improving processors and sensors, along with the growth of high-speed wireless data networks. Apps featuring augmented reality are available for everything from gaming to driving to furniture arrangement. Slowly but surely, augmented reality is becoming less of a novelty and more of a utility.

While the term is only just becoming common parlance among consumers, augmented reality’s history stretches back years: it has long been an area of academic research. Boeing used it with head-mounted displays in the 1990s to aid in aircraft wiring assembly (see “Look, Listen, Walk,” “Giving Soldiers a Better View,” and “Cyborg Seeks Community”).

Early augmented-reality smartphone apps used a device’s GPS and digital compass to determine your location and direction. More recently, app makers have begun incorporating computer vision and increasingly powerful processors to provide greater accuracy.

Jon Fisher, CEO and cofounder of San Francisco-based CrowdOptic, is one entrepreneur trying to take augmented reality mainstream. His startup’s software can recognize the direction in which a crowd of people have their phones pointed while taking photos or videos at events, and invite the group to communicate, share content, or get more information about the object of their attention, via an app.

The software uses a smartphone’s GPS, accelerometer, and compass to determine a user’s position and line of site; but also to triangulate with other phones using the same software to determine specifically what everyone in a cluster is looking at. The company’s technology has been used in a number of apps, including one for a recent NASCAR race in which fans, who couldn’t see the entire 2.5-mile track, could point their phones at distant turns and get photos and videos generated by others who were closer to the action.

Another company, iOnRoad, offers an augmented-reality collision-warning app for drivers using smartphones that run Google’s Android software (an iPhone version is in the works).

IOnRoad CEO Alon Atsmon says the app uses the phone’s camera stream along with image processing software to identify relevant objects like the lane in which you’re driving and the position of the car in front of you. GPS on your phone determines your speed. The app measures the distance between you and the car in front of you, and divides this by your speed to get a time gap. If the gap is perceived as too small, iOnRoad will warn you that you’re not keeping enough distance. Among other things, the app can determine what lane you’re driving in, and give you a warning if you start to drift, he says.

So far, nearly 500,000 people have downloaded the Android app since it was released late last year. Most of those chose a free version over a premium one that costs $4.99.

Moves by major companies—Google in particular—have helped make augmented reality seem less far-fetched. This spring, Google confirmed it is working on glasses that can show maps, messages, and other data to the wearer (see “You Will Want Google Goggles”). In June, Google started allowing developers to preorder, for $1,500, a prototype called Project Glass that will be available in early 2013. While not strictly focused on augmented reality, Project Glass draws attention to the idea of a digital layer on top of the physical world.

“Definitely, the attention is good,” says Pattie Maes, a professor at MIT’s Media Lab who has done extensive research on augmented reality. “It will motivate all the other consumer electronics companies and cell-phone companies to look at this a lot more seriously.”

For augmented reality to really become popular, however, a widespread number of apps will have to adopt it. Creative Strategies analyst Ben Bajarin believes the breakthrough could be apps for museums or zoos—while standing cage-side, you might hold up your smartphone to learn more about a bear or a giraffe, for example.

In fact, several zoos and museums already have experimented with the technology. At Toronto’s Royal Ontario Museum, for example, visitors can use iPads at a dinosaur exhibit to see how the beasts would have looked in real life. And augmented reality is about to get its biggest mass-market push yet: Swedish furniture maker Ikea’s 2013 catalog, 211 million copies of which were shipped out Wednesday, includes additional content that readers can see with an Android or iOS app.

The move could be a good one, Bajarin says, assuming it works well. “You don’t want people to try it and hate it, and go, ‘Eh, I’m not going to use that again,’ ” he says.