LAS VEGAS - In only a few years, smartphones and tablets have dramatically altered how people connect with one another via the Internet. This year's International Consumer Electronics Show, which opens here Tuesday, illustrates how the next frontier centers on using the Web to connect devices.

The long-heralded "Internet of things" is finally taking center stage.

Interconnected devices were everywhere this weekend as journalists and bloggers got an early look at some of the 3,200 exhibitors expected to draw 150,000 visitors to the massive show.

The key is the declining price and increasing ubiquity of all sorts of sensors - thermostats, cameras, motion sensors, and the like - that can be embedded just about anywhere and send data to the Internet.

Even flexible electronics sewn into fabrics are entering the mainstream. At the other end of the size spectrum, Ford and two other companies will demonstrate driverless cars - one of the long-range promises of the Internet of things.

Want to benefit now? Athletes can wear headgear equipped with mobile sensors that measure and report impacts - data that could raise crucial flags about potential concussions from hard hits in football, hockey, or other sports. Reebok offers the technology in the $150 CheckLight, created in partnership with MC10 Inc., of Cambridge, Mass.

Reebok and MC10 - founded by a University of Illinois scientist, John Rogers, who invented a stretchable circuit - won one of the Consumer Electronics Association's Innovations 2014 awards for design and engineering.

The Internet of things can help with energy savings, too. Remember Nest, the "learning thermostat" that was among the stars of last year's CES? This fall, Texas-based Allure Energy came to market with a $399 competitor, EverSense, that uses smartphone data to keep tabs on family members' whereabouts, then cranks up the heating or cooling as they get close to home.

Vice president Jim Mills said Allure had patented a learning thermostat similar to the $249 Nest, which learns your preferences without a complicated programming process, but chose another tack. Rather than predicting your desires, it adapts.

"No matter what you do, nothing can predict what's going to happen to you next week or what your activities will be," Mills said Sunday at CES Unveiled, a preview event that showcases dozens of innovations chosen each year by show planners.

Health and fitness companies have pioneered consumer uses for the Internet of things, and they aren't slowing. Nor are many of those who wear devices such as the $50 Fitbug Orb, which tracks both movement and sleep, and was launched at last year's show.

Fergus Kee, executive chairman of London's Fitbug Holdings Plc, was back this year to highlight his company's latest offering: a series of 12-week personal-training apps that rely on the Fitbug Orb to track progress. He said Fitbug wanted to focus on how new tools can be used rather than on a race over "who can have the flashiest device with the most bells and whistles."

The first app, No More Baby Belly, is due this spring and designed for new mothers who want to slim down. Other planned titles, which will start at $20, include Ready for the Big Day, a pre-wedding program; Back to Fitness for back strengthening; and sports-specific programs such as Ski Fit and Golf Gorgeous.

Embedded sensors are the key to another set of sports tools from Zepp Labs Inc., of Los Gatos, Calif., designed to improve your mechanics at golf, tennis, or baseball.

Zepp vice president Tom Fortunato said the company has taken a different approach from the makers of 94Fifty Smart Sensor Basketball, a $300 basketball that won an Innovations 2014 award. The 94Fifty ball is fitted with nine embedded sensors that send instant feedback on your ballhandling and shooting - even measuring your jump shot's arc - to your iPhone or iPad.

For half that price, Zepp puts a single sensor onto a golf glove, tennis racket, or baseball bat. That sensor, which can be used for more than one sport, captures data such as your bat speed, swing plane, and impact angle as you hit the ball of your choice. Zepp's software can then help you improve your game, Fortunato said.

Tara Dunion, a CES spokeswoman, said the digital-health category grew even faster than digital fitness this year, up 40 percent to 215 exhibitors.

A continuing theme, with new twists, is using the Internet to help keep tabs on the aged or ailing. Devices such as Lively, for instance, use sensors on pillboxes, refrigerators, and key chains to track whether a person appears to be following routines. If they aren't, the device can alert a caregiver.

"I even saw a toothbrush unveiled last night that has sensors, so I can prove to my kids that they're not brushing often enough," Dunion said.