10% of U.S. adults access the Internet solely through smartphones, according to “Home Broadband 2013,” a new report from the Pew Internet & American Life Project.

24% of U.S. adults only access the Internet through home broadband connections, Pew says. 46% access the Internet through home broadband and smartphones. And 20% do not access the web via home broadband or smartphones (this group includes dial-up web users and adults who do not use the Internet).

“Including smartphones in our broadband definition actually exacerbates differences in broadband adoption rates between young and old,” writes Kathryn Zickuhr, Pew research associate and lead author of the report. “Adding smartphone ownership to home broadband use, we see that the proportion of young adults who have home broadband under this definition increases from 80% to 95%, while including smartphones has no discernible impact on access rates for seniors—the 46% of seniors who have broadband or a smartphone is little different from the 43% who have broadband.”

In fact, it’s younger consumers driving the trend toward smartphone-only Internet access, mobile experts say.

“The smartphone-only users are primarily a younger demographic, 18-29,” says Tony Danova, an analyst at mobile technology research firm BI Intelligence, based on Pew data. “Historically, U.S. adults in that age bracket earn less income, are more mobile, and are less likely to be homeowners. They would rather pay for a cheaper, more portable form of Internet service than being bound to home broadband. Also, above all else, the quality of 4G and LTE mobile Internet connections have skyrocketed recently, and their availability across the country is growing, meaning fewer people have to depend on home broadband for quality Internet.”

The most common wireless network speed for smartphones is 3G, though 4G and 4G LTE are growing. 3G, which stands for third-generation wireless, transfers data at at least 200 kilobits per second. 4G, which stands for fourth-generation wireless, is considered mobile broadband and transfers data at 100 megabits per second. And 4G LTE, which stands for fourth-generation wireless long term evolution, is a telecommunications standard also considered mobile broadband and transfers data at 300 megabits per second.

Web retailers should pay close attention to the number of smartphone-only web users because it points to how consumers are changing how they use the Internet, and in many cases switching to mobile commerce, Danova says.

“Online retailers should definitely be keen on this movement,” he says. “On top of the general trend toward mobile devices, having 10% of U.S. adults accessing the Internet only via smartphones is further evidence that retailers need to tailor their shopping experiences for a growing mobile audience. Every relevant Internet retailer should invest in a quality mobile site and/or app that is optimized for shopping on smartphones and tablets.”

Favorite