Do you know anyone who doesn't use the Internet?
In the past decade, we've seen the invention and increasing popularity of mobile devices like smartphones, tablets and e-readers; the explosive growth of social networking sites like Facebook, which are now used by 72 percent of Internet users in the U.S.; and the more recent introduction of newer services that combine these mobile and social trends in various permutations, such as Twitter, Instagram, Foursquare, and Snapchat.
As we watch the rise, fall and evolution of countless online services and digital technologies, it's easy to assume that everyone is online. But a small and persistent swath of Americans remain offline—15 percent of adults ages 18 and older, as of May—and in most cases were never online to begin with.
This is especially relevant considering the types of content and services increasingly available only online, some targeted at the kinds of populations who are offline. Many government services, forms and information are increasingly moving online. And digital skills are often required to apply for jobs that themselves don't involve technology, in the form of requiring applicants to fill out online applications and file digital resumes to websites. In addition, the basic insights that drive commercial and civic decisions are being derived from online polls and various "big data" projects that take account of the views and activities only of those who use the Internet. That makes offline adults effectively invisible.
(Read more: Silicon Valley's next big market: Zimbabwe)
Yes, income and education make a difference
As with many technology adoption trends, Internet use remains strongly correlated with age, education and household income. Groups with lower levels of Internet adoption than average include:
•Adults ages 65 and older (56 percent use the Internet)
•Adults who did not complete high school (59 percent) and those who completed high school but did not attend college (78 percent)
•Hispanic adults (76 percent)
•Adults in households earning less than $30,000 per year (76 percent)
While seniors account for almost half of offline adults overall, age isn't the whole story. For instance, most non-Internet users did not attend college; offline adults are also more likely to be retired than their online counterparts, and more likely to live in lower-income households in general.
(Read more: LinkedIn's elder endorsers)
We see the impact of education and income most clearly when we look at older adults' Internet habits by education and household income. Among college graduates ages 65 and older, 85 percent use the Internet (a proportion on par with the general population). And among seniors living in households earning at least $50,000 per year, 83 percent are online.
On the other hand, the majority of seniors with lower education and income levels remain offline, including 62 percent of those 65 and older who did not attend college, and 55 percent of seniors in households earning less than $50,000 per year.
Reasons for staying offline
Are offline adults abstaining from Internet use due to a lack of interest, or are they prevented from logging on due to a lack of access? Even with our latest data, it's a tricky question to sort out.
On the one hand, roughly a third of offline adults' most commonly cited reasons for not using the Internet relate to a perceived lack of relevance, such as saying they are not interested, do not want to use it or have no need for it. And in response to a separate question, just 8 percent of non-Internet users said they would like to start using the Internet or email in the future.
(Read more: Paying cash costs Americans $200 billion a year)
On the other hand, the majority of offline adults cite reasons other than personal preference for remaining offline, including about a third who said that they wouldn't know how to use the Internet, or that it just seems too hard to use—and a higher proportion of non-Internet users cited these general "usability" issues than in previous years.
Finally, most offline adults have not used the Internet in the past (just 14 percent say this), and most don't live in a household where someone else goes online (23 percent say this). In other words, most offline adults have not had much personal experience with using the Internet or email, or see someone else using it at home. Additionally, the majority of offline adults say they would not be able to start using the Internet without assistance.
In sum, while most of these offline adults don't cite price or a lack of physical access to the Internet as the main reason they don't go online, their general lack of experience with and knowledge of the online world suggest that most would not be able to choose to go online tomorrow if they wished.
—By Kathryn Zickuhr, Research Associate, Pew Research Center's Internet Project
