(Nadine Hutton/Bloomberg)

Of the next six adults you meet, chances are one of them has never sent an e-mail. He's never done a Google search, never been Rickrolled. He thinks "doge" refers to a historical Italian government official. (Wow; very anachronism.)

He will probably never read this story.

It might seem inconceivable that in 2015 there could still be Americans who don't use the Internet — but they exist. Far from being irrelevant to modern society, they're increasingly the target of millions, if not billions, of dollars of taxpayer and private funding for Internet access. And that makes them a really important slice of the population.

[Here's Obama's plan to give teachers and libraries $1 billion a year in extra funding]

Who are these people?

Mostly they're poorer, older and undereducated, according to the Pew Research Center's latest figures. Fifteen percent of U.S. adults, or about 37 million people, by the Census Bureau's latest count, don't use the Web. But break it down by race and class, and suddenly the numbers look very bleak: A fifth of black Americans are disconnected. Same goes for the 25 percent of Americans who make less than $30,000 a year and a quarter of all adults who live in rural areas. And among those who've never finished high school, a third never use the Web.

As the rest of us use the Internet to do homework, find jobs, make friends, get the news, earn a living, learn new skills, buy groceries, organize politically and do a seemingly endless range of other activities, encouraging the disconnected to hop online has become a national priority. New programs are being launched all the time in Washington to expand Internet access, sometimes by federal agencies that would appear to have nothing to do with the Internet.

[Why the Agriculture Department is giving out tens of millions of dollars for Internet access]

The Federal Communications Commission recently opened a proceeding that would subsidize Internet plans for poor people. It has expanded its broadband funding for schools and libraries by $1 billion a year. The Department of Housing and Urban development is working with Google, Sprint and other Internet providers to put discount broadband services in public housing projects.

All these projects are aimed at accelerating a trend that's held consistently since the turn of the millennium. In 2000, nearly half of Americans didn't use the Web, according to Pew. Now that the figure stands at 15 percent, it's clear we've come a long way.

[The government found a smart way to connect the poor to the Internet: Put it in public housing]

But these remaining holdouts are likely to be the hardest to reach, because you can't just throw money at them. Of non-Internet users surveyed in 2013, just 19 percent cited the cost of Internet or owning a computer as an obstacle to adoption. Many more, 34 percent, said they didn't find the Internet relevant to them (though with seemingly 99.9 percent of the Web devoted to cat GIFs, perhaps they have a point). Thirty-two percent said the Web was too difficult to use, according to Pew.

Federal studies have shown that although 10 million disconnected Americans might be willing to get online at the right price, that still leaves some 27 million people for whom price is practically irrelevant to their decision to stay offline.

[How cheap does the Internet have to be to get everyone online?]

"If you build it, they will come," goes the adage. But for these folks, simply building out the Internet isn't enough; convincing them that the Web could help them grow is crucial to getting them online. And it's not merely a matter of waiting for old fuddy-duddies who don't "get it" to die off: As the data show, older people have been among the quickest to adopt the Internet among the disconnected population.

By contrast, there are real structural challenges (poverty and inequality) that are keeping younger, less socially mobile populations from becoming America's next great inventors or scientists or civil servants. And those people matter, too.